diff --git a/composer.json b/composer.json
index 6d9159b..2afb468 100644
--- a/composer.json
+++ b/composer.json
@@ -29,7 +29,11 @@
         "sabre/event": "^5.0",
         "felixfbecker/advanced-json-rpc": "^2.0",
         "squizlabs/php_codesniffer" : "^2.7",
-        "symfony/debug": "^3.1"
+        "symfony/debug": "^3.1",
+        "netresearch/jsonmapper": "^1.0",
+        "webmozart/path-util": "^2.3",
+        "webmozart/glob": "^4.1",
+        "sabre/uri": "^2.0"
     },
     "minimum-stability": "dev",
     "prefer-stable": true,
diff --git a/fixtures/recursive/a.txt b/fixtures/recursive/a.txt
deleted file mode 100644
index 8c7e5a6..0000000
--- a/fixtures/recursive/a.txt
+++ /dev/null
@@ -1 +0,0 @@
-A
\ No newline at end of file
diff --git a/fixtures/recursive/search/b.txt b/fixtures/recursive/search/b.txt
deleted file mode 100644
index 7371f47..0000000
--- a/fixtures/recursive/search/b.txt
+++ /dev/null
@@ -1 +0,0 @@
-B
\ No newline at end of file
diff --git a/fixtures/recursive/search/here/c.txt b/fixtures/recursive/search/here/c.txt
deleted file mode 100644
index d5274b3..0000000
--- a/fixtures/recursive/search/here/c.txt
+++ /dev/null
@@ -1 +0,0 @@
-Peeakboo!
\ No newline at end of file
diff --git a/src/Client/TextDocument.php b/src/Client/TextDocument.php
index d5314e4..176c4fd 100644
--- a/src/Client/TextDocument.php
+++ b/src/Client/TextDocument.php
@@ -4,8 +4,9 @@ declare(strict_types = 1);
 namespace LanguageServer\Client;
 
 use LanguageServer\ClientHandler;
-use LanguageServer\Protocol\Message;
+use LanguageServer\Protocol\{Message, TextDocumentItem, TextDocumentIdentifier};
 use Sabre\Event\Promise;
+use JsonMapper;
 
 /**
  * Provides method handlers for all textDocument/* methods
@@ -17,9 +18,15 @@ class TextDocument
      */
     private $handler;
 
-    public function __construct(ClientHandler $handler)
+    /**
+     * @var JsonMapper
+     */
+    private $mapper;
+
+    public function __construct(ClientHandler $handler, JsonMapper $mapper)
     {
         $this->handler = $handler;
+        $this->mapper = $mapper;
     }
 
     /**
@@ -36,4 +43,21 @@ class TextDocument
             'diagnostics' => $diagnostics
         ]);
     }
+
+    /**
+     * The content request is sent from a server to a client
+     * to request the current content of a text document identified by the URI
+     *
+     * @param TextDocumentIdentifier $textDocument The document to get the content for
+     * @return Promise <TextDocumentItem> The document's current content
+     */
+    public function xcontent(TextDocumentIdentifier $textDocument): Promise
+    {
+        return $this->handler->request(
+            'textDocument/xcontent',
+            ['textDocument' => $textDocument]
+        )->then(function ($result) {
+            return $this->mapper->map($result, new TextDocumentItem);
+        });
+    }
 }
diff --git a/src/Client/Workspace.php b/src/Client/Workspace.php
new file mode 100644
index 0000000..901e386
--- /dev/null
+++ b/src/Client/Workspace.php
@@ -0,0 +1,47 @@
+<?php
+declare(strict_types = 1);
+
+namespace LanguageServer\Client;
+
+use LanguageServer\ClientHandler;
+use LanguageServer\Protocol\TextDocumentIdentifier;
+use Sabre\Event\Promise;
+use JsonMapper;
+
+/**
+ * Provides method handlers for all workspace/* methods
+ */
+class Workspace
+{
+    /**
+     * @var ClientHandler
+     */
+    private $handler;
+
+    /**
+     * @var JsonMapper
+     */
+    private $mapper;
+
+    public function __construct(ClientHandler $handler, JsonMapper $mapper)
+    {
+        $this->handler = $handler;
+        $this->mapper = $mapper;
+    }
+
+    /**
+     * Returns a list of all files in a directory
+     *
+     * @param string $base The base directory (defaults to the workspace)
+     * @return Promise <TextDocumentIdentifier[]> Array of documents
+     */
+    public function xfiles(string $base = null): Promise
+    {
+        return $this->handler->request(
+            'workspace/xfiles',
+            ['base' => $base]
+        )->then(function (array $textDocuments) {
+            return $this->mapper->mapArray($textDocuments, [], TextDocumentIdentifier::class);
+        });
+    }
+}
diff --git a/src/LanguageClient.php b/src/LanguageClient.php
index 1f3c42a..d21a9aa 100644
--- a/src/LanguageClient.php
+++ b/src/LanguageClient.php
@@ -3,6 +3,8 @@ declare(strict_types = 1);
 
 namespace LanguageServer;
 
+use JsonMapper;
+
 class LanguageClient
 {
     /**
@@ -19,11 +21,20 @@ class LanguageClient
      */
     public $window;
 
+    /**
+     * Handles workspace/* methods
+     *
+     * @var Client\Workspace
+     */
+    public $workspace;
+
     public function __construct(ProtocolReader $reader, ProtocolWriter $writer)
     {
         $handler = new ClientHandler($reader, $writer);
+        $mapper = new JsonMapper;
 
-        $this->textDocument = new Client\TextDocument($handler);
+        $this->textDocument = new Client\TextDocument($handler, $mapper);
         $this->window = new Client\Window($handler);
+        $this->workspace = new Client\Workspace($handler, $mapper);
     }
 }
diff --git a/src/LanguageServer.php b/src/LanguageServer.php
index ddcddc7..9a89066 100644
--- a/src/LanguageServer.php
+++ b/src/LanguageServer.php
@@ -10,12 +10,18 @@ use LanguageServer\Protocol\{
     Message,
     MessageType,
     InitializeResult,
-    SymbolInformation
+    SymbolInformation,
+    TextDocumentIdentifier
 };
 use AdvancedJsonRpc;
-use Sabre\Event\Loop;
+use Sabre\Event\{Loop, Promise};
+use function Sabre\Event\coroutine;
 use Exception;
 use Throwable;
+use Webmozart\Glob\Iterator\GlobIterator;
+use Webmozart\Glob\Glob;
+use Webmozart\PathUtil\Path;
+use Sabre\Uri;
 
 class LanguageServer extends AdvancedJsonRpc\Dispatcher
 {
@@ -38,6 +44,11 @@ class LanguageServer extends AdvancedJsonRpc\Dispatcher
     public $completionItem;
     public $codeLens;
 
+    /**
+     * ClientCapabilities
+     */
+    private $clientCapabilities;
+
     private $protocolReader;
     private $protocolWriter;
     private $client;
@@ -55,40 +66,42 @@ class LanguageServer extends AdvancedJsonRpc\Dispatcher
         parent::__construct($this, '/');
         $this->protocolReader = $reader;
         $this->protocolReader->on('message', function (Message $msg) {
-            // Ignore responses, this is the handler for requests and notifications
-            if (AdvancedJsonRpc\Response::isResponse($msg->body)) {
-                return;
-            }
-            $result = null;
-            $error = null;
-            try {
-                // Invoke the method handler to get a result
-                $result = $this->dispatch($msg->body);
-            } catch (AdvancedJsonRpc\Error $e) {
-                // If a ResponseError is thrown, send it back in the Response
-                $error = $e;
-            } catch (Throwable $e) {
-                // If an unexpected error occured, send back an INTERNAL_ERROR error response
-                $error = new AdvancedJsonRpc\Error($e->getMessage(), AdvancedJsonRpc\ErrorCode::INTERNAL_ERROR, null, $e);
-            }
-            // Only send a Response for a Request
-            // Notifications do not send Responses
-            if (AdvancedJsonRpc\Request::isRequest($msg->body)) {
-                if ($error !== null) {
-                    $responseBody = new AdvancedJsonRpc\ErrorResponse($msg->body->id, $error);
-                } else {
-                    $responseBody = new AdvancedJsonRpc\SuccessResponse($msg->body->id, $result);
+            coroutine(function () use ($msg) {
+                // Ignore responses, this is the handler for requests and notifications
+                if (AdvancedJsonRpc\Response::isResponse($msg->body)) {
+                    return;
                 }
-                $this->protocolWriter->write(new Message($responseBody));
-            }
+                $result = null;
+                $error = null;
+                try {
+                    // Invoke the method handler to get a result
+                    $result = yield $this->dispatch($msg->body);
+                } catch (AdvancedJsonRpc\Error $e) {
+                    // If a ResponseError is thrown, send it back in the Response
+                    $error = $e;
+                } catch (Throwable $e) {
+                    // If an unexpected error occured, send back an INTERNAL_ERROR error response
+                    $error = new AdvancedJsonRpc\Error(
+                        $e->getMessage(),
+                        AdvancedJsonRpc\ErrorCode::INTERNAL_ERROR,
+                        null,
+                        $e
+                    );
+                }
+                // Only send a Response for a Request
+                // Notifications do not send Responses
+                if (AdvancedJsonRpc\Request::isRequest($msg->body)) {
+                    if ($error !== null) {
+                        $responseBody = new AdvancedJsonRpc\ErrorResponse($msg->body->id, $error);
+                    } else {
+                        $responseBody = new AdvancedJsonRpc\SuccessResponse($msg->body->id, $result);
+                    }
+                    $this->protocolWriter->write(new Message($responseBody));
+                }
+            })->otherwise('\\LanguageServer\\crash');
         });
         $this->protocolWriter = $writer;
         $this->client = new LanguageClient($reader, $writer);
-
-        $this->project = new Project($this->client);
-
-        $this->textDocument = new Server\TextDocument($this->project, $this->client);
-        $this->workspace = new Server\Workspace($this->project, $this->client);
     }
 
     /**
@@ -102,10 +115,14 @@ class LanguageServer extends AdvancedJsonRpc\Dispatcher
     public function initialize(int $processId, ClientCapabilities $capabilities, string $rootPath = null): InitializeResult
     {
         $this->rootPath = $rootPath;
+        $this->clientCapabilities = $capabilities;
+        $this->project = new Project($this->client, $capabilities);
+        $this->textDocument = new Server\TextDocument($this->project, $this->client);
+        $this->workspace = new Server\Workspace($this->project, $this->client);
 
         // start building project index
         if ($rootPath !== null) {
-            $this->indexProject();
+            $this->indexProject()->otherwise('\\LanguageServer\\crash');
         }
 
         $serverCapabilities = new ServerCapabilities();
@@ -136,6 +153,7 @@ class LanguageServer extends AdvancedJsonRpc\Dispatcher
      */
     public function shutdown()
     {
+        unset($this->project);
     }
 
     /**
@@ -151,42 +169,71 @@ class LanguageServer extends AdvancedJsonRpc\Dispatcher
     /**
      * Parses workspace files, one at a time.
      *
-     * @return void
+     * @return Promise <void>
      */
-    private function indexProject()
+    private function indexProject(): Promise
     {
-        $fileList = findFilesRecursive($this->rootPath, '/^.+\.php$/i');
-        $numTotalFiles = count($fileList);
+        return coroutine(function () {
+            $textDocuments = yield $this->findPhpFiles();
+            $count = count($textDocuments);
 
-        $startTime = microtime(true);
-        $fileNum = 0;
+            $startTime = microtime(true);
 
-        $processFile = function () use (&$fileList, &$fileNum, &$processFile, $numTotalFiles, $startTime) {
-            if ($fileNum < $numTotalFiles) {
-                $file = $fileList[$fileNum];
-                $uri = pathToUri($file);
-                $fileNum++;
-                $shortName = substr($file, strlen($this->rootPath) + 1);
-
-                if (filesize($file) > 500000) {
-                    $this->client->window->logMessage(MessageType::INFO, "Not parsing $shortName because it exceeds size limit of 0.5MB");
-                } else {
-                    $this->client->window->logMessage(MessageType::INFO, "Parsing file $fileNum/$numTotalFiles: $shortName.");
+            yield Promise\all(array_map(function ($textDocument, $i) use ($count) {
+                return coroutine(function () use ($textDocument, $i, $count) {
+                    // Give LS to the chance to handle requests while indexing
+                    yield timeout();
+                    $this->client->window->logMessage(
+                        MessageType::INFO,
+                        "Parsing file $i/$count: {$textDocument->uri}"
+                    );
                     try {
-                        $this->project->loadDocument($uri);
+                        yield $this->project->loadDocument($textDocument->uri);
                     } catch (Exception $e) {
-                        $this->client->window->logMessage(MessageType::ERROR, "Error parsing file $shortName: " . (string)$e);
+                        $this->client->window->logMessage(
+                            MessageType::ERROR,
+                            "Error parsing file {$textDocument->uri}: " . (string)$e
+                        );
+                    }
+                });
+            }, $textDocuments, array_keys($textDocuments)));
+
+            $duration = (int)(microtime(true) - $startTime);
+            $mem = (int)(memory_get_usage(true) / (1024 * 1024));
+            $this->client->window->logMessage(
+                MessageType::INFO,
+                "All $count PHP files parsed in $duration seconds. $mem MiB allocated."
+            );
+        });
+    }
+
+    /**
+     * Returns all PHP files in the workspace.
+     * If the client does not support workspace/files, it falls back to searching the file system directly.
+     *
+     * @return Promise <TextDocumentIdentifier[]>
+     */
+    private function findPhpFiles(): Promise
+    {
+        return coroutine(function () {
+            $textDocuments = [];
+            $pattern = Path::makeAbsolute('**/*.php', $this->rootPath);
+            if ($this->clientCapabilities->xfilesProvider) {
+                // Use xfiles request
+                foreach (yield $this->client->workspace->xfiles() as $textDocument) {
+                    $path = Uri\parse($textDocument->uri)['path'];
+                    if (Glob::match($path, $pattern)) {
+                        $textDocuments[] = $textDocument;
                     }
                 }
-
-                Loop\setTimeout($processFile, 0);
             } else {
-                $duration = (int)(microtime(true) - $startTime);
-                $mem = (int)(memory_get_usage(true) / (1024 * 1024));
-                $this->client->window->logMessage(MessageType::INFO, "All $numTotalFiles PHP files parsed in $duration seconds. $mem MiB allocated.");
+                // Use the file system
+                foreach (new GlobIterator($pattern) as $path) {
+                    $textDocuments[] = new TextDocumentIdentifier(pathToUri($path));
+                    yield timeout();
+                }
             }
-        };
-
-        Loop\setTimeout($processFile, 0);
+            return $textDocuments;
+        });
     }
 }
diff --git a/src/PhpDocument.php b/src/PhpDocument.php
index 5033959..75badca 100644
--- a/src/PhpDocument.php
+++ b/src/PhpDocument.php
@@ -17,6 +17,8 @@ use PhpParser\{Error, ErrorHandler, Node, NodeTraverser};
 use PhpParser\NodeVisitor\NameResolver;
 use phpDocumentor\Reflection\DocBlockFactory;
 use function LanguageServer\Fqn\{getDefinedFqn, getVariableDefinition, getReferencedFqn};
+use Sabre\Event\Promise;
+use function Sabre\Event\coroutine;
 
 class PhpDocument
 {
@@ -314,34 +316,36 @@ class PhpDocument
      * The definition node MAY be in another document, check the ownerDocument attribute
      *
      * @param Node $node
-     * @return Node|null
+     * @return Promise <Node|null>
      */
-    public function getDefinitionByNode(Node $node)
+    public function getDefinitionByNode(Node $node): Promise
     {
-        // Variables always stay in the boundary of the file and need to be searched inside their function scope
-        // by traversing the AST
-        if ($node instanceof Node\Expr\Variable) {
-            return getVariableDefinition($node);
-        }
-        $fqn = getReferencedFqn($node);
-        if (!isset($fqn)) {
-            return null;
-        }
-        $document = $this->project->getDefinitionDocument($fqn);
-        if (!isset($document)) {
-            // If the node is a function or constant, it could be namespaced, but PHP falls back to global
-            // http://php.net/manual/en/language.namespaces.fallback.php
-            $parent = $node->getAttribute('parentNode');
-            if ($parent instanceof Node\Expr\ConstFetch || $parent instanceof Node\Expr\FuncCall) {
-                $parts = explode('\\', $fqn);
-                $fqn = end($parts);
-                $document = $this->project->getDefinitionDocument($fqn);
+        return coroutine(function () use ($node) {
+            // Variables always stay in the boundary of the file and need to be searched inside their function scope
+            // by traversing the AST
+            if ($node instanceof Node\Expr\Variable) {
+                return getVariableDefinition($node);
             }
-        }
-        if (!isset($document)) {
-            return null;
-        }
-        return $document->getDefinitionByFqn($fqn);
+            $fqn = getReferencedFqn($node);
+            if (!isset($fqn)) {
+                return null;
+            }
+            $document = yield $this->project->getDefinitionDocument($fqn);
+            if (!isset($document)) {
+                // If the node is a function or constant, it could be namespaced, but PHP falls back to global
+                // http://php.net/manual/en/language.namespaces.fallback.php
+                $parent = $node->getAttribute('parentNode');
+                if ($parent instanceof Node\Expr\ConstFetch || $parent instanceof Node\Expr\FuncCall) {
+                    $parts = explode('\\', $fqn);
+                    $fqn = end($parts);
+                    $document = yield $this->project->getDefinitionDocument($fqn);
+                }
+            }
+            if (!isset($document)) {
+                return null;
+            }
+            return $document->getDefinitionByFqn($fqn);
+        });
     }
 
     /**
@@ -349,45 +353,47 @@ class PhpDocument
      * The references node MAY be in other documents, check the ownerDocument attribute
      *
      * @param Node $node
-     * @return Node[]
+     * @return Promise <Node[]>
      */
-    public function getReferencesByNode(Node $node)
+    public function getReferencesByNode(Node $node): Promise
     {
-        // Variables always stay in the boundary of the file and need to be searched inside their function scope
-        // by traversing the AST
-        if ($node instanceof Node\Expr\Variable || $node instanceof Node\Param) {
-            if ($node->name instanceof Node\Expr) {
-                return null;
+        return coroutine(function () use ($node) {
+            // Variables always stay in the boundary of the file and need to be searched inside their function scope
+            // by traversing the AST
+            if ($node instanceof Node\Expr\Variable || $node instanceof Node\Param) {
+                if ($node->name instanceof Node\Expr) {
+                    return null;
+                }
+                // Find function/method/closure scope
+                $n = $node;
+                while (isset($n) && !($n instanceof Node\FunctionLike)) {
+                    $n = $n->getAttribute('parentNode');
+                }
+                if (!isset($n)) {
+                    $n = $node->getAttribute('ownerDocument');
+                }
+                $traverser = new NodeTraverser;
+                $refCollector = new VariableReferencesCollector($node->name);
+                $traverser->addVisitor($refCollector);
+                $traverser->traverse($n->getStmts());
+                return $refCollector->references;
             }
-            // Find function/method/closure scope
-            $n = $node;
-            while (isset($n) && !($n instanceof Node\FunctionLike)) {
-                $n = $n->getAttribute('parentNode');
+            // Definition with a global FQN
+            $fqn = getDefinedFqn($node);
+            if ($fqn === null) {
+                return [];
             }
-            if (!isset($n)) {
-                $n = $node->getAttribute('ownerDocument');
-            }
-            $traverser = new NodeTraverser;
-            $refCollector = new VariableReferencesCollector($node->name);
-            $traverser->addVisitor($refCollector);
-            $traverser->traverse($n->getStmts());
-            return $refCollector->references;
-        }
-        // Definition with a global FQN
-        $fqn = getDefinedFqn($node);
-        if ($fqn === null) {
-            return [];
-        }
-        $refDocuments = $this->project->getReferenceDocuments($fqn);
-        $nodes = [];
-        foreach ($refDocuments as $document) {
-            $refs = $document->getReferencesByFqn($fqn);
-            if ($refs !== null) {
-                foreach ($refs as $ref) {
-                    $nodes[] = $ref;
+            $refDocuments = yield $this->project->getReferenceDocuments($fqn);
+            $nodes = [];
+            foreach ($refDocuments as $document) {
+                $refs = $document->getReferencesByFqn($fqn);
+                if ($refs !== null) {
+                    foreach ($refs as $ref) {
+                        $nodes[] = $ref;
+                    }
                 }
             }
-        }
-        return $nodes;
+            return $nodes;
+        });
     }
 }
diff --git a/src/Project.php b/src/Project.php
index 0a5349f..e6c1dbd 100644
--- a/src/Project.php
+++ b/src/Project.php
@@ -3,8 +3,10 @@ declare(strict_types = 1);
 
 namespace LanguageServer;
 
-use LanguageServer\Protocol\SymbolInformation;
+use LanguageServer\Protocol\{SymbolInformation, TextDocumentIdentifier, ClientCapabilities};
 use phpDocumentor\Reflection\DocBlockFactory;
+use Sabre\Event\Promise;
+use function Sabre\Event\coroutine;
 
 class Project
 {
@@ -51,47 +53,69 @@ class Project
      */
     private $client;
 
-    public function __construct(LanguageClient $client)
+    /**
+     * The client's capabilities
+     *
+     * @var ClientCapabilities
+     */
+    private $clientCapabilities;
+
+    public function __construct(LanguageClient $client, ClientCapabilities $clientCapabilities)
     {
         $this->client = $client;
-
+        $this->clientCapabilities = $clientCapabilities;
         $this->parser = new Parser;
         $this->docBlockFactory = DocBlockFactory::createInstance();
     }
 
     /**
      * Returns the document indicated by uri.
-     * If the document is not open, tries to read it from disk, but the document is not added the list of open documents.
+     * Returns null if the document if not loaded.
      *
      * @param string $uri
-     * @return LanguageServer\PhpDocument
+     * @return PhpDocument|null
      */
     public function getDocument(string $uri)
     {
-        if (!isset($this->documents[$uri])) {
-            return $this->loadDocument($uri);
-        } else {
-            return $this->documents[$uri];
-        }
+        return $this->documents[$uri] ?? null;
     }
 
     /**
-     * Reads a document from disk.
+     * Returns the document indicated by uri.
+     * If the document is not open, loads it.
+     *
+     * @param string $uri
+     * @return Promise <PhpDocument>
+     */
+    public function getOrLoadDocument(string $uri)
+    {
+        return isset($this->documents[$uri]) ? Promise\resolve($this->documents[$uri]) : $this->loadDocument($uri);
+    }
+
+    /**
+     * Loads the document by doing a textDocument/xcontent request to the client.
+     * If the client does not support textDocument/xcontent, tries to read the file from the file system.
      * The document is NOT added to the list of open documents, but definitions are registered.
      *
      * @param string $uri
-     * @return LanguageServer\PhpDocument
+     * @return Promise <PhpDocument>
      */
-    public function loadDocument(string $uri)
+    public function loadDocument(string $uri): Promise
     {
-        $content = file_get_contents(uriToPath($uri));
-        if (isset($this->documents[$uri])) {
-            $document = $this->documents[$uri];
-            $document->updateContent($content);
-        } else {
-            $document = new PhpDocument($uri, $content, $this, $this->client, $this->parser, $this->docBlockFactory);
-        }
-        return $document;
+        return coroutine(function () use ($uri) {
+            if ($this->clientCapabilities->xcontentProvider) {
+                $content = (yield $this->client->textDocument->xcontent(new TextDocumentIdentifier($uri)))->text;
+            } else {
+                $content = file_get_contents(uriToPath($uri));
+            }
+            if (isset($this->documents[$uri])) {
+                $document = $this->documents[$uri];
+                $document->updateContent($content);
+            } else {
+                $document = new PhpDocument($uri, $content, $this, $this->client, $this->parser, $this->docBlockFactory);
+            }
+            return $document;
+        });
     }
 
     /**
@@ -222,14 +246,14 @@ class Project
      * Returns all documents that reference a symbol
      *
      * @param string $fqn The fully qualified name of the symbol
-     * @return PhpDocument[]
+     * @return Promise <PhpDocument[]>
      */
-    public function getReferenceDocuments(string $fqn)
+    public function getReferenceDocuments(string $fqn): Promise
     {
         if (!isset($this->references[$fqn])) {
-            return [];
+            return Promise\resolve([]);
         }
-        return array_map([$this, 'getDocument'], $this->references[$fqn]);
+        return Promise\all(array_map([$this, 'getOrLoadDocument'], $this->references[$fqn]));
     }
 
     /**
@@ -258,11 +282,14 @@ class Project
      * Returns the document where a symbol is defined
      *
      * @param string $fqn The fully qualified name of the symbol
-     * @return PhpDocument|null
+     * @return Promise <PhpDocument|null>
      */
-    public function getDefinitionDocument(string $fqn)
+    public function getDefinitionDocument(string $fqn): Promise
     {
-        return isset($this->symbols[$fqn]) ? $this->getDocument($this->symbols[$fqn]->location->uri) : null;
+        if (!isset($this->symbols[$fqn])) {
+            return Promise\resolve(null);
+        }
+        return $this->getOrLoadDocument($this->symbols[$fqn]->location->uri);
     }
 
     /**
diff --git a/src/Protocol/ClientCapabilities.php b/src/Protocol/ClientCapabilities.php
index c85e44b..42137e9 100644
--- a/src/Protocol/ClientCapabilities.php
+++ b/src/Protocol/ClientCapabilities.php
@@ -4,5 +4,17 @@ namespace LanguageServer\Protocol;
 
 class ClientCapabilities
 {
+    /**
+     * The client supports workspace/xfiles requests
+     *
+     * @var bool|null
+     */
+    public $xfilesProvider;
 
+    /**
+     * The client supports textDocument/xcontent requests
+     *
+     * @var bool|null
+     */
+    public $xcontentProvider;
 }
diff --git a/src/Server/TextDocument.php b/src/Server/TextDocument.php
index 188e629..1fc8f27 100644
--- a/src/Server/TextDocument.php
+++ b/src/Server/TextDocument.php
@@ -3,7 +3,7 @@ declare(strict_types = 1);
 
 namespace LanguageServer\Server;
 
-use LanguageServer\{LanguageClient, Project};
+use LanguageServer\{LanguageClient, Project, PhpDocument};
 use PhpParser\PrettyPrinter\Standard as PrettyPrinter;
 use PhpParser\Node;
 use LanguageServer\Protocol\{
@@ -20,6 +20,8 @@ use LanguageServer\Protocol\{
     Hover,
     MarkedString
 };
+use Sabre\Event\Promise;
+use function Sabre\Event\coroutine;
 
 /**
  * Provides method handlers for all textDocument/* methods
@@ -55,11 +57,13 @@ class TextDocument
      * document.
      *
      * @param \LanguageServer\Protocol\TextDocumentIdentifier $textDocument
-     * @return SymbolInformation[]
+     * @return Promise <SymbolInformation[]>
      */
-    public function documentSymbol(TextDocumentIdentifier $textDocument): array
+    public function documentSymbol(TextDocumentIdentifier $textDocument): Promise
     {
-        return array_values($this->project->getDocument($textDocument->uri)->getSymbols());
+        return $this->project->getOrLoadDocument($textDocument->uri)->then(function (PhpDocument $document) {
+            return array_values($document->getSymbols());
+        });
     }
 
     /**
@@ -105,11 +109,13 @@ class TextDocument
      *
      * @param TextDocumentIdentifier $textDocument The document to format
      * @param FormattingOptions $options The format options
-     * @return TextEdit[]
+     * @return Promise <TextEdit[]>
      */
     public function formatting(TextDocumentIdentifier $textDocument, FormattingOptions $options)
     {
-        return $this->project->getDocument($textDocument->uri)->getFormattedText();
+        return $this->project->getOrLoadDocument($textDocument->uri)->then(function (PhpDocument $document) {
+            return $document->getFormattedText();
+        });
     }
 
     /**
@@ -117,21 +123,26 @@ class TextDocument
      * denoted by the given text document position.
      *
      * @param ReferenceContext $context
-     * @return Location[]
+     * @return Promise <Location[]>
      */
-    public function references(ReferenceContext $context, TextDocumentIdentifier $textDocument, Position $position): array
-    {
-        $document = $this->project->getDocument($textDocument->uri);
-        $node = $document->getNodeAtPosition($position);
-        if ($node === null) {
-            return [];
-        }
-        $refs = $document->getReferencesByNode($node);
-        $locations = [];
-        foreach ($refs as $ref) {
-            $locations[] = Location::fromNode($ref);
-        }
-        return $locations;
+    public function references(
+        ReferenceContext $context,
+        TextDocumentIdentifier $textDocument,
+        Position $position
+    ): Promise {
+        return coroutine(function () use ($textDocument, $position) {
+            $document = yield $this->project->getOrLoadDocument($textDocument->uri);
+            $node = $document->getNodeAtPosition($position);
+            if ($node === null) {
+                return [];
+            }
+            $refs = yield $document->getReferencesByNode($node);
+            $locations = [];
+            foreach ($refs as $ref) {
+                $locations[] = Location::fromNode($ref);
+            }
+            return $locations;
+        });
     }
 
     /**
@@ -140,20 +151,22 @@ class TextDocument
      *
      * @param TextDocumentIdentifier $textDocument The text document
      * @param Position $position The position inside the text document
-     * @return Location|Location[]
+     * @return Promise <Location|Location[]>
      */
-    public function definition(TextDocumentIdentifier $textDocument, Position $position)
+    public function definition(TextDocumentIdentifier $textDocument, Position $position): Promise
     {
-        $document = $this->project->getDocument($textDocument->uri);
-        $node = $document->getNodeAtPosition($position);
-        if ($node === null) {
-            return [];
-        }
-        $def = $document->getDefinitionByNode($node);
-        if ($def === null) {
-            return [];
-        }
-        return Location::fromNode($def);
+        return coroutine(function () use ($textDocument, $position) {
+            $document = yield $this->project->getOrLoadDocument($textDocument->uri);
+            $node = $document->getNodeAtPosition($position);
+            if ($node === null) {
+                return [];
+            }
+            $def = yield $document->getDefinitionByNode($node);
+            if ($def === null) {
+                return [];
+            }
+            return Location::fromNode($def);
+        });
     }
 
     /**
@@ -161,66 +174,68 @@ class TextDocument
      *
      * @param TextDocumentIdentifier $textDocument The text document
      * @param Position $position The position inside the text document
-     * @return Hover
+     * @return Promise <Hover>
      */
-    public function hover(TextDocumentIdentifier $textDocument, Position $position): Hover
+    public function hover(TextDocumentIdentifier $textDocument, Position $position): Promise
     {
-        $document = $this->project->getDocument($textDocument->uri);
-        // Find the node under the cursor
-        $node = $document->getNodeAtPosition($position);
-        if ($node === null) {
-            return new Hover([]);
-        }
-        $range = Range::fromNode($node);
-        // Get the definition node for whatever node is under the cursor
-        $def = $document->getDefinitionByNode($node);
-        if ($def === null) {
-            return new Hover([], $range);
-        }
-        $contents = [];
+        return coroutine(function () use ($textDocument, $position) {
+            $document = yield $this->project->getOrLoadDocument($textDocument->uri);
+            // Find the node under the cursor
+            $node = $document->getNodeAtPosition($position);
+            if ($node === null) {
+                return new Hover([]);
+            }
+            $range = Range::fromNode($node);
+            // Get the definition node for whatever node is under the cursor
+            $def = yield $document->getDefinitionByNode($node);
+            if ($def === null) {
+                return new Hover([], $range);
+            }
+            $contents = [];
 
-        // Build a declaration string
-        if ($def instanceof Node\Stmt\PropertyProperty || $def instanceof Node\Const_) {
-            // Properties and constants can have multiple declarations
-            // Use the parent node (that includes the modifiers), but only render the requested declaration
-            $child = $def;
-            $def = $def->getAttribute('parentNode');
-            $defLine = clone $def;
-            $defLine->props = [$child];
-        } else {
-            $defLine = clone $def;
-        }
-        // Don't include the docblock in the declaration string
-        $defLine->setAttribute('comments', []);
-        if (isset($defLine->stmts)) {
-            $defLine->stmts = [];
-        }
-        $defText = $this->prettyPrinter->prettyPrint([$defLine]);
-        $lines = explode("\n", $defText);
-        if (isset($lines[0])) {
-            $contents[] = new MarkedString('php', "<?php\n" . $lines[0]);
-        }
+            // Build a declaration string
+            if ($def instanceof Node\Stmt\PropertyProperty || $def instanceof Node\Const_) {
+                // Properties and constants can have multiple declarations
+                // Use the parent node (that includes the modifiers), but only render the requested declaration
+                $child = $def;
+                $def = $def->getAttribute('parentNode');
+                $defLine = clone $def;
+                $defLine->props = [$child];
+            } else {
+                $defLine = clone $def;
+            }
+            // Don't include the docblock in the declaration string
+            $defLine->setAttribute('comments', []);
+            if (isset($defLine->stmts)) {
+                $defLine->stmts = [];
+            }
+            $defText = $this->prettyPrinter->prettyPrint([$defLine]);
+            $lines = explode("\n", $defText);
+            if (isset($lines[0])) {
+                $contents[] = new MarkedString('php', "<?php\n" . $lines[0]);
+            }
 
-        // Get the documentation string
-        if ($def instanceof Node\Param) {
-            $fn = $def->getAttribute('parentNode');
-            $docBlock = $fn->getAttribute('docBlock');
-            if ($docBlock !== null) {
-                $tags = $docBlock->getTagsByName('param');
-                foreach ($tags as $tag) {
-                    if ($tag->getVariableName() === $def->name) {
-                        $contents[] = $tag->getDescription()->render();
-                        break;
+            // Get the documentation string
+            if ($def instanceof Node\Param) {
+                $fn = $def->getAttribute('parentNode');
+                $docBlock = $fn->getAttribute('docBlock');
+                if ($docBlock !== null) {
+                    $tags = $docBlock->getTagsByName('param');
+                    foreach ($tags as $tag) {
+                        if ($tag->getVariableName() === $def->name) {
+                            $contents[] = $tag->getDescription()->render();
+                            break;
+                        }
                     }
                 }
+            } else {
+                $docBlock = $def->getAttribute('docBlock');
+                if ($docBlock !== null) {
+                    $contents[] = $docBlock->getSummary();
+                }
             }
-        } else {
-            $docBlock = $def->getAttribute('docBlock');
-            if ($docBlock !== null) {
-                $contents[] = $docBlock->getSummary();
-            }
-        }
 
-        return new Hover($contents, $range);
+            return new Hover($contents, $range);
+        });
     }
 }
diff --git a/src/utils.php b/src/utils.php
index 58b07ea..061eff7 100644
--- a/src/utils.php
+++ b/src/utils.php
@@ -3,26 +3,9 @@ declare(strict_types = 1);
 
 namespace LanguageServer;
 
+use Throwable;
 use InvalidArgumentException;
-
-/**
- * Recursively Searches files with matching filename, starting at $path.
- *
- * @param string $path
- * @param string $pattern
- * @return array
- */
-function findFilesRecursive(string $path, string $pattern): array
-{
-    $dir = new \RecursiveDirectoryIterator($path);
-    $ite = new \RecursiveIteratorIterator($dir);
-    $files = new \RegexIterator($ite, $pattern, \RegexIterator::GET_MATCH);
-    $fileList = [];
-    foreach ($files as $file) {
-        $fileList = array_merge($fileList, $file);
-    }
-    return $fileList;
-}
+use Sabre\Event\{Loop, Promise};
 
 /**
  * Transforms an absolute file path into a URI as used by the language server protocol.
@@ -66,3 +49,31 @@ function uriToPath(string $uri)
     }
     return $filepath;
 }
+
+/**
+ * Throws an exception on the next tick.
+ * Useful for letting a promise crash the process on rejection.
+ *
+ * @param Throwable $err
+ * @return void
+ */
+function crash(Throwable $err)
+{
+    Loop\nextTick(function () use ($err) {
+        throw $err;
+    });
+}
+
+/**
+ * Returns a promise that is resolved after x seconds.
+ * Useful for giving back control to the event loop inside a coroutine.
+ *
+ * @param int $seconds
+ * @return Promise <void>
+ */
+function timeout($seconds = 0): Promise
+{
+    $promise = new Promise;
+    Loop\setTimeout([$promise, 'fulfill'], $seconds);
+    return $promise;
+}
diff --git a/tests/LanguageServerTest.php b/tests/LanguageServerTest.php
index 3f0c314..8456713 100644
--- a/tests/LanguageServerTest.php
+++ b/tests/LanguageServerTest.php
@@ -5,9 +5,13 @@ namespace LanguageServer\Tests;
 
 use PHPUnit\Framework\TestCase;
 use LanguageServer\LanguageServer;
-use LanguageServer\Protocol\{Message, ClientCapabilities, TextDocumentSyncKind, MessageType};
+use LanguageServer\Protocol\{
+    Message, ClientCapabilities, TextDocumentSyncKind, MessageType, TextDocumentItem, TextDocumentIdentifier};
 use AdvancedJsonRpc;
+use Webmozart\Glob\Glob;
+use Webmozart\PathUtil\Path;
 use Sabre\Event\Promise;
+use Exception;
 use function LanguageServer\pathToUri;
 
 class LanguageServerTest extends TestCase
@@ -17,15 +21,14 @@ class LanguageServerTest extends TestCase
         $reader = new MockProtocolStream();
         $writer = new MockProtocolStream();
         $server = new LanguageServer($reader, $writer);
-        $msg = null;
-        $writer->on('message', function (Message $message) use (&$msg) {
-            $msg = $message;
-        });
+        $promise = new Promise;
+        $writer->once('message', [$promise, 'fulfill']);
         $reader->write(new Message(new AdvancedJsonRpc\Request(1, 'initialize', [
             'rootPath' => __DIR__,
             'processId' => getmypid(),
             'capabilities' => new ClientCapabilities()
         ])));
+        $msg = $promise->wait();
         $this->assertNotNull($msg, 'message event should be emitted');
         $this->assertInstanceOf(AdvancedJsonRpc\SuccessResponse::class, $msg->body);
         $this->assertEquals((object)[
@@ -49,7 +52,7 @@ class LanguageServerTest extends TestCase
         ], $msg->body->result);
     }
 
-    public function testIndexing()
+    public function testIndexingWithDirectFileAccess()
     {
         $promise = new Promise;
         $input = new MockProtocolStream;
@@ -68,4 +71,54 @@ class LanguageServerTest extends TestCase
         $server->initialize(getmypid(), $capabilities, realpath(__DIR__ . '/../fixtures'));
         $promise->wait();
     }
+
+    public function testIndexingWithFilesAndContentRequests()
+    {
+        $promise = new Promise;
+        $filesCalled = false;
+        $contentCalled = false;
+        $rootPath = realpath(__DIR__ . '/../fixtures');
+        $input = new MockProtocolStream;
+        $output = new MockProtocolStream;
+        $output->on('message', function (Message $msg) use ($promise, $input, $rootPath, &$filesCalled, &$contentCalled) {
+            if ($msg->body->method === 'textDocument/xcontent') {
+                // Document content requested
+                $contentCalled = true;
+                $textDocumentItem = new TextDocumentItem;
+                $textDocumentItem->uri = $msg->body->params->textDocument->uri;
+                $textDocumentItem->version = 1;
+                $textDocumentItem->languageId = 'php';
+                $textDocumentItem->text = file_get_contents($msg->body->params->textDocument->uri);
+                $input->write(new Message(new AdvancedJsonRpc\SuccessResponse($msg->body->id, $textDocumentItem)));
+            } else if ($msg->body->method === 'workspace/xfiles') {
+                // Files requested
+                $filesCalled = true;
+                $pattern = Path::makeAbsolute('**/*.php', $msg->body->params->base ?? $rootPath);
+                $files = [];
+                foreach (Glob::glob($pattern) as $path) {
+                    $files[] = new TextDocumentIdentifier(pathToUri($path));
+                }
+                $input->write(new Message(new AdvancedJsonRpc\SuccessResponse($msg->body->id, $files)));
+            } else if ($msg->body->method === 'window/logMessage') {
+                // Message logged
+                if ($msg->body->params->type === MessageType::ERROR) {
+                    // Error happened during indexing, fail test
+                    if ($promise->state === Promise::PENDING) {
+                        $promise->reject(new Exception($msg->body->params->message));
+                    }
+                } else if (strpos($msg->body->params->message, 'All 10 PHP files parsed') !== false) {
+                    // Indexing finished
+                    $promise->fulfill();
+                }
+            }
+        });
+        $server = new LanguageServer($input, $output);
+        $capabilities = new ClientCapabilities;
+        $capabilities->xfilesProvider = true;
+        $capabilities->xcontentProvider = true;
+        $server->initialize(getmypid(), $capabilities, $rootPath);
+        $promise->wait();
+        $this->assertTrue($filesCalled);
+        $this->assertTrue($contentCalled);
+    }
 }
diff --git a/tests/MockProtocolStream.php b/tests/MockProtocolStream.php
index 5550b3f..b2a489d 100644
--- a/tests/MockProtocolStream.php
+++ b/tests/MockProtocolStream.php
@@ -5,7 +5,7 @@ namespace LanguageServer\Tests;
 
 use LanguageServer\{ProtocolReader, ProtocolWriter};
 use LanguageServer\Protocol\Message;
-use Sabre\Event\{Emitter, Promise};
+use Sabre\Event\{Loop, Emitter, Promise};
 
 /**
  * A fake duplex protocol stream
@@ -20,7 +20,9 @@ class MockProtocolStream extends Emitter implements ProtocolReader, ProtocolWrit
      */
     public function write(Message $msg): Promise
     {
-        $this->emit('message', [Message::parse((string)$msg)]);
+        Loop\nextTick(function () use ($msg) {
+            $this->emit('message', [Message::parse((string)$msg)]);
+        });
         return Promise\resolve(null);
     }
 }
diff --git a/tests/NodeVisitor/DefinitionCollectorTest.php b/tests/NodeVisitor/DefinitionCollectorTest.php
index 0a8fdb1..6df5940 100644
--- a/tests/NodeVisitor/DefinitionCollectorTest.php
+++ b/tests/NodeVisitor/DefinitionCollectorTest.php
@@ -7,6 +7,7 @@ use PHPUnit\Framework\TestCase;
 use PhpParser\{NodeTraverser, Node};
 use PhpParser\NodeVisitor\NameResolver;
 use LanguageServer\{LanguageClient, Project, PhpDocument, Parser};
+use LanguageServer\Protocol\ClientCapabilities;
 use LanguageServer\Tests\MockProtocolStream;
 use LanguageServer\NodeVisitor\{ReferencesAdder, DefinitionCollector};
 use function LanguageServer\pathToUri;
@@ -16,10 +17,10 @@ class DefinitionCollectorTest extends TestCase
     public function testCollectsSymbols()
     {
         $client = new LanguageClient(new MockProtocolStream, new MockProtocolStream);
-        $project = new Project($client);
+        $project = new Project($client, new ClientCapabilities);
         $parser = new Parser;
         $uri = pathToUri(realpath(__DIR__ . '/../../fixtures/symbols.php'));
-        $document = $project->loadDocument($uri);
+        $document = $project->loadDocument($uri)->wait();
         $traverser = new NodeTraverser;
         $traverser->addVisitor(new NameResolver);
         $traverser->addVisitor(new ReferencesAdder($document));
@@ -55,10 +56,10 @@ class DefinitionCollectorTest extends TestCase
     public function testDoesNotCollectReferences()
     {
         $client = new LanguageClient(new MockProtocolStream, new MockProtocolStream);
-        $project = new Project($client);
+        $project = new Project($client, new ClientCapabilities);
         $parser = new Parser;
         $uri = pathToUri(realpath(__DIR__ . '/../../fixtures/references.php'));
-        $document = $project->loadDocument($uri);
+        $document = $project->loadDocument($uri)->wait();
         $traverser = new NodeTraverser;
         $traverser->addVisitor(new NameResolver);
         $traverser->addVisitor(new ReferencesAdder($document));
diff --git a/tests/PhpDocumentTest.php b/tests/PhpDocumentTest.php
index fce5dc4..5cdc8c8 100644
--- a/tests/PhpDocumentTest.php
+++ b/tests/PhpDocumentTest.php
@@ -7,7 +7,7 @@ use PHPUnit\Framework\TestCase;
 use LanguageServer\Tests\MockProtocolStream;
 use LanguageServer\{LanguageClient, Project};
 use LanguageServer\NodeVisitor\NodeAtPositionFinder;
-use LanguageServer\Protocol\{SymbolKind, Position};
+use LanguageServer\Protocol\{SymbolKind, Position, ClientCapabilities};
 use PhpParser\Node;
 
 class PhpDocumentTest extends TestCase
@@ -19,7 +19,8 @@ class PhpDocumentTest extends TestCase
 
     public function setUp()
     {
-        $this->project = new Project(new LanguageClient(new MockProtocolStream, new MockProtocolStream));
+        $client = new LanguageClient(new MockProtocolStream, new MockProtocolStream);
+        $this->project = new Project($client, new ClientCapabilities);
     }
 
     public function testParsesVariableVariables()
diff --git a/tests/ProjectTest.php b/tests/ProjectTest.php
index dc030d2..161370c 100644
--- a/tests/ProjectTest.php
+++ b/tests/ProjectTest.php
@@ -6,7 +6,14 @@ namespace LanguageServer\Tests\Server;
 use PHPUnit\Framework\TestCase;
 use LanguageServer\Tests\MockProtocolStream;
 use LanguageServer\{Server, Client, LanguageClient, Project, PhpDocument};
-use LanguageServer\Protocol\{TextDocumentItem, TextDocumentIdentifier, SymbolKind, DiagnosticSeverity, FormattingOptions};
+use LanguageServer\Protocol\{
+    TextDocumentItem,
+    TextDocumentIdentifier,
+    SymbolKind,
+    DiagnosticSeverity,
+    FormattingOptions,
+    ClientCapabilities
+};
 use AdvancedJsonRpc\{Request as RequestBody, Response as ResponseBody};
 use function LanguageServer\pathToUri;
 
@@ -19,12 +26,13 @@ class ProjectTest extends TestCase
 
     public function setUp()
     {
-        $this->project = new Project(new LanguageClient(new MockProtocolStream, new MockProtocolStream));
+        $client = new LanguageClient(new MockProtocolStream, new MockProtocolStream);
+        $this->project = new Project($client, new ClientCapabilities);
     }
 
-    public function testGetDocumentLoadsDocument()
+    public function testGetOrLoadDocumentLoadsDocument()
     {
-        $document = $this->project->getDocument(pathToUri(__FILE__));
+        $document = $this->project->getOrLoadDocument(pathToUri(__FILE__))->wait();
 
         $this->assertNotNull($document);
         $this->assertInstanceOf(PhpDocument::class, $document);
diff --git a/tests/Server/ServerTestCase.php b/tests/Server/ServerTestCase.php
index 24095a3..c5818a9 100644
--- a/tests/Server/ServerTestCase.php
+++ b/tests/Server/ServerTestCase.php
@@ -6,8 +6,9 @@ namespace LanguageServer\Tests\Server;
 use PHPUnit\Framework\TestCase;
 use LanguageServer\Tests\MockProtocolStream;
 use LanguageServer\{Server, LanguageClient, Project};
-use LanguageServer\Protocol\{Position, Location, Range};
+use LanguageServer\Protocol\{Position, Location, Range, ClientCapabilities};
 use function LanguageServer\pathToUri;
+use Sabre\Event\Promise;
 
 abstract class ServerTestCase extends TestCase
 {
@@ -43,7 +44,7 @@ abstract class ServerTestCase extends TestCase
     public function setUp()
     {
         $client             = new LanguageClient(new MockProtocolStream, new MockProtocolStream);
-        $this->project      = new Project($client);
+        $this->project      = new Project($client, new ClientCapabilities);
         $this->textDocument = new Server\TextDocument($this->project, $client);
         $this->workspace    = new Server\Workspace($this->project, $client);
 
@@ -53,11 +54,13 @@ abstract class ServerTestCase extends TestCase
         $referencesUri       = pathToUri(realpath(__DIR__ . '/../../fixtures/references.php'));
         $useUri              = pathToUri(realpath(__DIR__ . '/../../fixtures/use.php'));
 
-        $this->project->loadDocument($symbolsUri);
-        $this->project->loadDocument($referencesUri);
-        $this->project->loadDocument($globalSymbolsUri);
-        $this->project->loadDocument($globalReferencesUri);
-        $this->project->loadDocument($useUri);
+        Promise\all([
+            $this->project->loadDocument($symbolsUri),
+            $this->project->loadDocument($referencesUri),
+            $this->project->loadDocument($globalSymbolsUri),
+            $this->project->loadDocument($globalReferencesUri),
+            $this->project->loadDocument($useUri)
+        ])->wait();
 
         // @codingStandardsIgnoreStart
         $this->definitionLocations = [
diff --git a/tests/Server/TextDocument/Definition/GlobalFallbackTest.php b/tests/Server/TextDocument/Definition/GlobalFallbackTest.php
index ea62f70..c4b021d 100644
--- a/tests/Server/TextDocument/Definition/GlobalFallbackTest.php
+++ b/tests/Server/TextDocument/Definition/GlobalFallbackTest.php
@@ -6,14 +6,15 @@ namespace LanguageServer\Tests\Server\TextDocument\Definition;
 use LanguageServer\Tests\MockProtocolStream;
 use LanguageServer\Tests\Server\ServerTestCase;
 use LanguageServer\{Server, LanguageClient, Project};
-use LanguageServer\Protocol\{TextDocumentIdentifier, Position, Range, Location};
+use LanguageServer\Protocol\{TextDocumentIdentifier, Position, Range, Location, ClientCapabilities};
+use Sabre\Event\Promise;
 
 class GlobalFallbackTest extends ServerTestCase
 {
     public function setUp()
     {
         $client = new LanguageClient(new MockProtocolStream, new MockProtocolStream);
-        $project = new Project($client);
+        $project = new Project($client, new ClientCapabilities);
         $this->textDocument = new Server\TextDocument($project, $client);
         $project->openDocument('global_fallback', file_get_contents(__DIR__ . '/../../../../fixtures/global_fallback.php'));
         $project->openDocument('global_symbols', file_get_contents(__DIR__ . '/../../../../fixtures/global_symbols.php'));
@@ -23,7 +24,10 @@ class GlobalFallbackTest extends ServerTestCase
     {
         // $obj = new TestClass();
         // Get definition for TestClass should not fall back to global
-        $result = $this->textDocument->definition(new TextDocumentIdentifier('global_fallback'), new Position(9, 16));
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier('global_fallback'),
+            new Position(9, 16)
+        )->wait();
         $this->assertEquals([], $result);
     }
 
@@ -31,7 +35,10 @@ class GlobalFallbackTest extends ServerTestCase
     {
         // echo TEST_CONST;
         // Get definition for TEST_CONST
-        $result = $this->textDocument->definition(new TextDocumentIdentifier('global_fallback'), new Position(6, 10));
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier('global_fallback'),
+            new Position(6, 10)
+        )->wait();
         $this->assertEquals(new Location('global_symbols', new Range(new Position(9, 6), new Position(9, 22))), $result);
     }
 
@@ -39,7 +46,10 @@ class GlobalFallbackTest extends ServerTestCase
     {
         // test_function();
         // Get definition for test_function
-        $result = $this->textDocument->definition(new TextDocumentIdentifier('global_fallback'), new Position(5, 6));
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier('global_fallback'),
+            new Position(5, 6)
+        )->wait();
         $this->assertEquals(new Location('global_symbols', new Range(new Position(78, 0), new Position(81, 1))), $result);
     }
 }
diff --git a/tests/Server/TextDocument/Definition/GlobalTest.php b/tests/Server/TextDocument/Definition/GlobalTest.php
index ded6f38..bc5f6e6 100644
--- a/tests/Server/TextDocument/Definition/GlobalTest.php
+++ b/tests/Server/TextDocument/Definition/GlobalTest.php
@@ -12,14 +12,20 @@ class GlobalTest extends ServerTestCase
     public function testDefinitionFileBeginning()
     {
         // |<?php
-        $result = $this->textDocument->definition(new TextDocumentIdentifier(pathToUri(realpath(__DIR__ . '/../../../../fixtures/references.php'))), new Position(0, 0));
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier(pathToUri(realpath(__DIR__ . '/../../../../fixtures/references.php'))),
+            new Position(0, 0)
+        )->wait();
         $this->assertEquals([], $result);
     }
 
     public function testDefinitionEmptyResult()
     {
         // namespace keyword
-        $result = $this->textDocument->definition(new TextDocumentIdentifier(pathToUri(realpath(__DIR__ . '/../../../../fixtures/references.php'))), new Position(2, 4));
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier(pathToUri(realpath(__DIR__ . '/../../../../fixtures/references.php'))),
+            new Position(2, 4)
+        )->wait();
         $this->assertEquals([], $result);
     }
 
@@ -28,7 +34,10 @@ class GlobalTest extends ServerTestCase
         // $obj = new TestClass();
         // Get definition for TestClass
         $reference = $this->getReferenceLocations('TestClass')[0];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->start);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->start
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestClass'), $result);
     }
 
@@ -37,7 +46,10 @@ class GlobalTest extends ServerTestCase
         // TestClass::staticTestMethod();
         // Get definition for TestClass
         $reference = $this->getReferenceLocations('TestClass')[1];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->start);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->start
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestClass'), $result);
     }
 
@@ -46,7 +58,10 @@ class GlobalTest extends ServerTestCase
         // echo TestClass::$staticTestProperty;
         // Get definition for TestClass
         $reference = $this->getReferenceLocations('TestClass')[2];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->start);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->start
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestClass'), $result);
     }
 
@@ -55,7 +70,10 @@ class GlobalTest extends ServerTestCase
         // TestClass::TEST_CLASS_CONST;
         // Get definition for TestClass
         $reference = $this->getReferenceLocations('TestClass')[3];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->start);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->start
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestClass'), $result);
     }
 
@@ -64,7 +82,10 @@ class GlobalTest extends ServerTestCase
         // class TestClass implements TestInterface
         // Get definition for TestInterface
         $reference = $this->getReferenceLocations('TestInterface')[0];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->start);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->start
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestInterface'), $result);
     }
 
@@ -73,7 +94,10 @@ class GlobalTest extends ServerTestCase
         // echo TestClass::TEST_CLASS_CONST;
         // Get definition for TEST_CLASS_CONST
         $reference = $this->getReferenceLocations('TestClass::TEST_CLASS_CONST')[1];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->end);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->end
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestClass::TEST_CLASS_CONST'), $result);
     }
 
@@ -82,7 +106,10 @@ class GlobalTest extends ServerTestCase
         // echo self::TEST_CLASS_CONST;
         // Get definition for TEST_CLASS_CONST
         $reference = $this->getReferenceLocations('TestClass::TEST_CLASS_CONST')[0];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->end);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->end
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestClass::TEST_CLASS_CONST'), $result);
     }
 
@@ -91,7 +118,10 @@ class GlobalTest extends ServerTestCase
         // echo TEST_CONST;
         // Get definition for TEST_CONST
         $reference = $this->getReferenceLocations('TEST_CONST')[1];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->start);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->start
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TEST_CONST'), $result);
     }
 
@@ -100,7 +130,10 @@ class GlobalTest extends ServerTestCase
         // TestClass::staticTestMethod();
         // Get definition for staticTestMethod
         $reference = $this->getReferenceLocations('TestClass::staticTestMethod()')[0];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->end);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->end
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestClass::staticTestMethod()'), $result);
     }
 
@@ -109,7 +142,10 @@ class GlobalTest extends ServerTestCase
         // echo TestClass::$staticTestProperty;
         // Get definition for staticTestProperty
         $reference = $this->getReferenceLocations('TestClass::staticTestProperty')[0];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->end);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->end
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestClass::staticTestProperty'), $result);
     }
 
@@ -118,7 +154,10 @@ class GlobalTest extends ServerTestCase
         // $obj->testMethod();
         // Get definition for testMethod
         $reference = $this->getReferenceLocations('TestClass::testMethod()')[0];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->end);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->end
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestClass::testMethod()'), $result);
     }
 
@@ -127,7 +166,10 @@ class GlobalTest extends ServerTestCase
         // echo $obj->testProperty;
         // Get definition for testProperty
         $reference = $this->getReferenceLocations('TestClass::testProperty')[1];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->end);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->end
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestClass::testProperty'), $result);
     }
 
@@ -136,7 +178,10 @@ class GlobalTest extends ServerTestCase
         // $this->testProperty = $testParameter;
         // Get definition for testProperty
         $reference = $this->getReferenceLocations('TestClass::testProperty')[0];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->end);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->end
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestClass::testProperty'), $result);
     }
 
@@ -145,7 +190,10 @@ class GlobalTest extends ServerTestCase
         // echo $var;
         // Get definition for $var
         $uri = pathToUri(realpath(__DIR__ . '/../../../../fixtures/references.php'));
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($uri), new Position(13, 7));
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($uri),
+            new Position(13, 7)
+        )->wait();
         $this->assertEquals(new Location($uri, new Range(new Position(12, 0), new Position(12, 10))), $result);
     }
 
@@ -154,7 +202,10 @@ class GlobalTest extends ServerTestCase
         // function whatever(TestClass $param) {
         // Get definition for TestClass
         $reference = $this->getReferenceLocations('TestClass')[4];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->start);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->start
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestClass'), $result);
     }
 
@@ -163,7 +214,10 @@ class GlobalTest extends ServerTestCase
         // function whatever(TestClass $param): TestClass {
         // Get definition for TestClass
         $reference = $this->getReferenceLocations('TestClass')[5];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->start);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->start
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestClass'), $result);
     }
 
@@ -172,7 +226,10 @@ class GlobalTest extends ServerTestCase
         // public function testMethod($testParameter): TestInterface
         // Get definition for TestInterface
         $reference = $this->getReferenceLocations('TestInterface')[1];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->start);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->start
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestInterface'), $result);
     }
 
@@ -181,7 +238,10 @@ class GlobalTest extends ServerTestCase
         // echo $param;
         // Get definition for $param
         $uri = pathToUri(realpath(__DIR__ . '/../../../../fixtures/references.php'));
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($uri), new Position(22, 13));
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($uri),
+            new Position(22, 13)
+        )->wait();
         $this->assertEquals(new Location($uri, new Range(new Position(21, 18), new Position(21, 34))), $result);
     }
 
@@ -190,7 +250,10 @@ class GlobalTest extends ServerTestCase
         // echo $var;
         // Get definition for $var
         $uri = pathToUri(realpath(__DIR__ . '/../../../../fixtures/references.php'));
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($uri), new Position(26, 11));
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($uri),
+            new Position(26, 11)
+        )->wait();
         $this->assertEquals(new Location($uri, new Range(new Position(25, 22), new Position(25, 26))), $result);
     }
 
@@ -199,7 +262,10 @@ class GlobalTest extends ServerTestCase
         // test_function();
         // Get definition for test_function
         $reference = $this->getReferenceLocations('test_function()')[0];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->start);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->start
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('test_function()'), $result);
     }
 
@@ -208,7 +274,10 @@ class GlobalTest extends ServerTestCase
         // use function test_function;
         // Get definition for test_function
         $reference = $this->getReferenceLocations('test_function()')[1];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->start);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->start
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('test_function()'), $result);
     }
 
@@ -217,7 +286,10 @@ class GlobalTest extends ServerTestCase
         // if ($abc instanceof TestInterface) {
         // Get definition for TestInterface
         $reference = $this->getReferenceLocations('TestInterface')[2];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->start);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->start
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestInterface'), $result);
     }
 }
diff --git a/tests/Server/TextDocument/Definition/NamespacedTest.php b/tests/Server/TextDocument/Definition/NamespacedTest.php
index e796ef9..ef66624 100644
--- a/tests/Server/TextDocument/Definition/NamespacedTest.php
+++ b/tests/Server/TextDocument/Definition/NamespacedTest.php
@@ -23,7 +23,10 @@ class NamespacedTest extends GlobalTest
         // echo TEST_CONST;
         // Get definition for TEST_CONST
         $reference = $this->getReferenceLocations('TEST_CONST')[0];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->start);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->start
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TEST_CONST'), $result);
     }
 
@@ -32,7 +35,10 @@ class NamespacedTest extends GlobalTest
         // use TestNamespace\TestClass;
         // Get definition for TestClass
         $reference = $this->getReferenceLocations('TestClass')[6];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->start);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->start
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestClass'), $result);
     }
 
@@ -41,7 +47,10 @@ class NamespacedTest extends GlobalTest
         // use TestNamespace\{TestTrait, TestInterface};
         // Get definition for TestInterface
         $reference = $this->getReferenceLocations('TestClass')[0];
-        $result = $this->textDocument->definition(new TextDocumentIdentifier($reference->uri), $reference->range->start);
+        $result = $this->textDocument->definition(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->start
+        )->wait();
         $this->assertEquals($this->getDefinitionLocation('TestClass'), $result);
     }
 }
diff --git a/tests/Server/TextDocument/DidChangeTest.php b/tests/Server/TextDocument/DidChangeTest.php
index 0ee62ef..1df0505 100644
--- a/tests/Server/TextDocument/DidChangeTest.php
+++ b/tests/Server/TextDocument/DidChangeTest.php
@@ -12,7 +12,8 @@ use LanguageServer\Protocol\{
     VersionedTextDocumentIdentifier,
     TextDocumentContentChangeEvent,
     Range,
-    Position
+    Position,
+    ClientCapabilities
 };
 
 class DidChangeTest extends TestCase
@@ -20,7 +21,7 @@ class DidChangeTest extends TestCase
     public function test()
     {
         $client = new LanguageClient(new MockProtocolStream, new MockProtocolStream);
-        $project = new Project($client);
+        $project = new Project($client, new ClientCapabilities);
         $textDocument = new Server\TextDocument($project, $client);
         $phpDocument = $project->openDocument('whatever', "<?php\necho 'Hello, World'\n");
 
diff --git a/tests/Server/TextDocument/DidCloseTest.php b/tests/Server/TextDocument/DidCloseTest.php
index fdd5136..7ec93f1 100644
--- a/tests/Server/TextDocument/DidCloseTest.php
+++ b/tests/Server/TextDocument/DidCloseTest.php
@@ -6,7 +6,7 @@ namespace LanguageServer\Tests\Server\TextDocument;
 use PHPUnit\Framework\TestCase;
 use LanguageServer\Tests\MockProtocolStream;
 use LanguageServer\{Server, Client, LanguageClient, Project};
-use LanguageServer\Protocol\{TextDocumentItem, TextDocumentIdentifier};
+use LanguageServer\Protocol\{TextDocumentItem, TextDocumentIdentifier, ClientCapabilities};
 use Exception;
 
 class DidCloseTest extends TestCase
@@ -14,7 +14,7 @@ class DidCloseTest extends TestCase
     public function test()
     {
         $client = new LanguageClient(new MockProtocolStream, new MockProtocolStream);
-        $project = new Project($client);
+        $project = new Project($client, new ClientCapabilities);
         $textDocument = new Server\TextDocument($project, $client);
         $phpDocument = $project->openDocument('whatever', 'hello world');
 
diff --git a/tests/Server/TextDocument/DocumentSymbolTest.php b/tests/Server/TextDocument/DocumentSymbolTest.php
index 7b304d0..4f09e20 100644
--- a/tests/Server/TextDocument/DocumentSymbolTest.php
+++ b/tests/Server/TextDocument/DocumentSymbolTest.php
@@ -15,7 +15,7 @@ class DocumentSymbolTest extends ServerTestCase
     {
         // Request symbols
         $uri = pathToUri(realpath(__DIR__ . '/../../../fixtures/symbols.php'));
-        $result = $this->textDocument->documentSymbol(new TextDocumentIdentifier($uri));
+        $result = $this->textDocument->documentSymbol(new TextDocumentIdentifier($uri))->wait();
         // @codingStandardsIgnoreStart
         $this->assertEquals([
             new SymbolInformation('TEST_CONST',         SymbolKind::CONSTANT,  $this->getDefinitionLocation('TestNamespace\\TEST_CONST'),                    'TestNamespace'),
diff --git a/tests/Server/TextDocument/FormattingTest.php b/tests/Server/TextDocument/FormattingTest.php
index ca6fc2c..b7d0609 100644
--- a/tests/Server/TextDocument/FormattingTest.php
+++ b/tests/Server/TextDocument/FormattingTest.php
@@ -6,7 +6,15 @@ namespace LanguageServer\Tests\Server\TextDocument;
 use PHPUnit\Framework\TestCase;
 use LanguageServer\Tests\MockProtocolStream;
 use LanguageServer\{Server, Client, LanguageClient, Project};
-use LanguageServer\Protocol\{TextDocumentIdentifier, TextDocumentItem, FormattingOptions};
+use LanguageServer\Protocol\{
+    TextDocumentIdentifier,
+    TextDocumentItem,
+    FormattingOptions,
+    ClientCapabilities,
+    TextEdit,
+    Range,
+    Position
+};
 use function LanguageServer\{pathToUri, uriToPath};
 
 class FormattingTest extends TestCase
@@ -19,14 +27,14 @@ class FormattingTest extends TestCase
     public function setUp()
     {
         $client = new LanguageClient(new MockProtocolStream, new MockProtocolStream);
-        $project = new Project($client);
+        $project = new Project($client, new ClientCapabilities);
         $this->textDocument = new Server\TextDocument($project, $client);
     }
 
     public function testFormatting()
     {
         $client = new LanguageClient(new MockProtocolStream, new MockProtocolStream);
-        $project = new Project($client);
+        $project = new Project($client, new ClientCapabilities);
         $textDocument = new Server\TextDocument($project, $client);
         $path = realpath(__DIR__ . '/../../../fixtures/format.php');
         $uri = pathToUri($path);
@@ -42,19 +50,7 @@ class FormattingTest extends TestCase
         // how code should look after formatting
         $expected = file_get_contents(__DIR__ . '/../../../fixtures/format_expected.php');
         // Request formatting
-        $result = $textDocument->formatting(new TextDocumentIdentifier($uri), new FormattingOptions());
-        $this->assertEquals([0 => [
-            'range' => [
-                'start' => [
-                    'line' => 0,
-                    'character' => 0
-                ],
-                'end' => [
-                    'line' => 20,
-                    'character' => 0
-                ]
-            ],
-            'newText' => $expected
-        ]], json_decode(json_encode($result), true));
+        $result = $textDocument->formatting(new TextDocumentIdentifier($uri), new FormattingOptions())->wait();
+        $this->assertEquals([new TextEdit(new Range(new Position(0, 0), new Position(20, 0)), $expected)], $result);
     }
 }
diff --git a/tests/Server/TextDocument/HoverTest.php b/tests/Server/TextDocument/HoverTest.php
index 20d59d0..80cef64 100644
--- a/tests/Server/TextDocument/HoverTest.php
+++ b/tests/Server/TextDocument/HoverTest.php
@@ -16,7 +16,10 @@ class HoverTest extends ServerTestCase
         // $obj = new TestClass();
         // Get hover for TestClass
         $reference = $this->getReferenceLocations('TestClass')[0];
-        $result = $this->textDocument->hover(new TextDocumentIdentifier($reference->uri), $reference->range->start);
+        $result = $this->textDocument->hover(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->start
+        )->wait();
         $this->assertEquals(new Hover([
             new MarkedString('php', "<?php\nclass TestClass implements \\TestInterface"),
             'Pariatur ut laborum tempor voluptate consequat ea deserunt.'
@@ -28,7 +31,10 @@ class HoverTest extends ServerTestCase
         // $obj->testMethod();
         // Get hover for testMethod
         $reference = $this->getReferenceLocations('TestClass::testMethod()')[0];
-        $result = $this->textDocument->hover(new TextDocumentIdentifier($reference->uri), $reference->range->end);
+        $result = $this->textDocument->hover(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->end
+        )->wait();
         $this->assertEquals(new Hover([
             new MarkedString('php', "<?php\npublic function testMethod(\$testParameter) : \TestInterface"),
             'Non culpa nostrud mollit esse sunt laboris in irure ullamco cupidatat amet.'
@@ -40,7 +46,10 @@ class HoverTest extends ServerTestCase
         // echo $obj->testProperty;
         // Get hover for testProperty
         $reference = $this->getReferenceLocations('TestClass::testProperty')[0];
-        $result = $this->textDocument->hover(new TextDocumentIdentifier($reference->uri), $reference->range->end);
+        $result = $this->textDocument->hover(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->end
+        )->wait();
         $this->assertEquals(new Hover([
             new MarkedString('php', "<?php\npublic \$testProperty;"),
             'Reprehenderit magna velit mollit ipsum do.'
@@ -52,7 +61,10 @@ class HoverTest extends ServerTestCase
         // TestClass::staticTestMethod();
         // Get hover for staticTestMethod
         $reference = $this->getReferenceLocations('TestClass::staticTestMethod()')[0];
-        $result = $this->textDocument->hover(new TextDocumentIdentifier($reference->uri), $reference->range->end);
+        $result = $this->textDocument->hover(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->end
+        )->wait();
         $this->assertEquals(new Hover([
             new MarkedString('php', "<?php\npublic static function staticTestMethod()"),
             'Do magna consequat veniam minim proident eiusmod incididunt aute proident.'
@@ -64,7 +76,10 @@ class HoverTest extends ServerTestCase
         // echo TestClass::staticTestProperty;
         // Get hover for staticTestProperty
         $reference = $this->getReferenceLocations('TestClass::staticTestProperty')[0];
-        $result = $this->textDocument->hover(new TextDocumentIdentifier($reference->uri), $reference->range->end);
+        $result = $this->textDocument->hover(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->end
+        )->wait();
         $this->assertEquals(new Hover([
             new MarkedString('php', "<?php\npublic static \$staticTestProperty;"),
             'Lorem excepteur officia sit anim velit veniam enim.'
@@ -76,7 +91,10 @@ class HoverTest extends ServerTestCase
         // echo TestClass::TEST_CLASS_CONST;
         // Get hover for TEST_CLASS_CONST
         $reference = $this->getReferenceLocations('TestClass::TEST_CLASS_CONST')[0];
-        $result = $this->textDocument->hover(new TextDocumentIdentifier($reference->uri), $reference->range->end);
+        $result = $this->textDocument->hover(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->end
+        )->wait();
         $this->assertEquals(new Hover([
             new MarkedString('php', "<?php\nconst TEST_CLASS_CONST = 123;"),
             'Anim labore veniam consectetur laboris minim quis aute aute esse nulla ad.'
@@ -88,7 +106,10 @@ class HoverTest extends ServerTestCase
         // test_function();
         // Get hover for test_function
         $reference = $this->getReferenceLocations('test_function()')[0];
-        $result = $this->textDocument->hover(new TextDocumentIdentifier($reference->uri), $reference->range->end);
+        $result = $this->textDocument->hover(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->end
+        )->wait();
         $this->assertEquals(new Hover([
             new MarkedString('php', "<?php\nfunction test_function()"),
             'Officia aliquip adipisicing et nulla et laboris dolore labore.'
@@ -100,7 +121,10 @@ class HoverTest extends ServerTestCase
         // echo TEST_CONST;
         // Get hover for TEST_CONST
         $reference = $this->getReferenceLocations('TEST_CONST')[0];
-        $result = $this->textDocument->hover(new TextDocumentIdentifier($reference->uri), $reference->range->end);
+        $result = $this->textDocument->hover(
+            new TextDocumentIdentifier($reference->uri),
+            $reference->range->end
+        )->wait();
         $this->assertEquals(new Hover([
             new MarkedString('php', "<?php\nconst TEST_CONST = 123;"),
             'Esse commodo excepteur pariatur Lorem est aute incididunt reprehenderit.'
@@ -112,7 +136,7 @@ class HoverTest extends ServerTestCase
         // echo $var;
         // Get hover for $var
         $uri = pathToUri(realpath(__DIR__ . '/../../../fixtures/references.php'));
-        $result = $this->textDocument->hover(new TextDocumentIdentifier($uri), new Position(13, 7));
+        $result = $this->textDocument->hover(new TextDocumentIdentifier($uri), new Position(13, 7))->wait();
         $this->assertEquals(new Hover(
             [new MarkedString('php', "<?php\n\$var = 123;")],
             new Range(new Position(13, 5), new Position(13, 9))
@@ -124,7 +148,7 @@ class HoverTest extends ServerTestCase
         // echo $param;
         // Get hover for $param
         $uri = pathToUri(realpath(__DIR__ . '/../../../fixtures/references.php'));
-        $result = $this->textDocument->hover(new TextDocumentIdentifier($uri), new Position(22, 11));
+        $result = $this->textDocument->hover(new TextDocumentIdentifier($uri), new Position(22, 11))->wait();
         $this->assertEquals(new Hover(
             [
                 new MarkedString('php', "<?php\n\TestNamespace\TestClass \$param"),
diff --git a/tests/Server/TextDocument/ParseErrorsTest.php b/tests/Server/TextDocument/ParseErrorsTest.php
index 128d58f..2a02efe 100644
--- a/tests/Server/TextDocument/ParseErrorsTest.php
+++ b/tests/Server/TextDocument/ParseErrorsTest.php
@@ -6,8 +6,9 @@ namespace LanguageServer\Tests\Server\TextDocument;
 use PHPUnit\Framework\TestCase;
 use LanguageServer\Tests\MockProtocolStream;
 use LanguageServer\{Server, Client, LanguageClient, Project, ClientHandler};
-use LanguageServer\Protocol\{TextDocumentIdentifier, TextDocumentItem, DiagnosticSeverity};
+use LanguageServer\Protocol\{TextDocumentIdentifier, TextDocumentItem, DiagnosticSeverity, ClientCapabilities};
 use Sabre\Event\Promise;
+use JsonMapper;
 
 class ParseErrorsTest extends TestCase
 {
@@ -25,7 +26,7 @@ class ParseErrorsTest extends TestCase
             private $args;
             public function __construct(&$args)
             {
-                parent::__construct(new ClientHandler(new MockProtocolStream, new MockProtocolStream));
+                parent::__construct(new ClientHandler(new MockProtocolStream, new MockProtocolStream), new JsonMapper);
                 $this->args = &$args;
             }
             public function publishDiagnostics(string $uri, array $diagnostics): Promise
@@ -34,7 +35,7 @@ class ParseErrorsTest extends TestCase
                 return Promise\resolve(null);
             }
         };
-        $project = new Project($client);
+        $project = new Project($client, new ClientCapabilities);
         $this->textDocument = new Server\TextDocument($project, $client);
     }
 
diff --git a/tests/Server/TextDocument/References/GlobalFallbackTest.php b/tests/Server/TextDocument/References/GlobalFallbackTest.php
index 6862d97..9f68cb9 100644
--- a/tests/Server/TextDocument/References/GlobalFallbackTest.php
+++ b/tests/Server/TextDocument/References/GlobalFallbackTest.php
@@ -6,7 +6,7 @@ namespace LanguageServer\Tests\Server\TextDocument\References;
 use PHPUnit\Framework\TestCase;
 use LanguageServer\Tests\MockProtocolStream;
 use LanguageServer\{Server, LanguageClient, Project};
-use LanguageServer\Protocol\{TextDocumentIdentifier, Position, ReferenceContext, Location, Range};
+use LanguageServer\Protocol\{TextDocumentIdentifier, Position, ReferenceContext, Location, Range, ClientCapabilities};
 use LanguageServer\Tests\Server\ServerTestCase;
 
 class GlobalFallbackTest extends ServerTestCase
@@ -14,7 +14,7 @@ class GlobalFallbackTest extends ServerTestCase
     public function setUp()
     {
         $client = new LanguageClient(new MockProtocolStream, new MockProtocolStream);
-        $project = new Project($client);
+        $project = new Project($client, new ClientCapabilities);
         $this->textDocument = new Server\TextDocument($project, $client);
         $project->openDocument('global_fallback', file_get_contents(__DIR__ . '/../../../../fixtures/global_fallback.php'));
         $project->openDocument('global_symbols', file_get_contents(__DIR__ . '/../../../../fixtures/global_symbols.php'));
@@ -24,7 +24,11 @@ class GlobalFallbackTest extends ServerTestCase
     {
         // class TestClass implements TestInterface
         // Get references for TestClass
-        $result = $this->textDocument->references(new ReferenceContext, new TextDocumentIdentifier('global_symbols'), new Position(6, 9));
+        $result = $this->textDocument->references(
+            new ReferenceContext,
+            new TextDocumentIdentifier('global_symbols'),
+            new Position(6, 9)
+        )->wait();
         $this->assertEquals([], $result);
     }
 
@@ -32,7 +36,11 @@ class GlobalFallbackTest extends ServerTestCase
     {
         // const TEST_CONST = 123;
         // Get references for TEST_CONST
-        $result = $this->textDocument->references(new ReferenceContext, new TextDocumentIdentifier('global_symbols'), new Position(9, 13));
+        $result = $this->textDocument->references(
+            new ReferenceContext,
+            new TextDocumentIdentifier('global_symbols'),
+            new Position(9, 13)
+        )->wait();
         $this->assertEquals([new Location('global_fallback', new Range(new Position(6, 5), new Position(6, 15)))], $result);
     }
 
@@ -40,7 +48,11 @@ class GlobalFallbackTest extends ServerTestCase
     {
         // function test_function()
         // Get references for test_function
-        $result = $this->textDocument->references(new ReferenceContext, new TextDocumentIdentifier('global_symbols'), new Position(78, 16));
+        $result = $this->textDocument->references(
+            new ReferenceContext,
+            new TextDocumentIdentifier('global_symbols'),
+            new Position(78, 16)
+        )->wait();
         $this->assertEquals([new Location('global_fallback', new Range(new Position(5, 0), new Position(5, 13)))], $result);
     }
 }
diff --git a/tests/Server/TextDocument/References/GlobalTest.php b/tests/Server/TextDocument/References/GlobalTest.php
index 1ecf1f9..bf6eb97 100644
--- a/tests/Server/TextDocument/References/GlobalTest.php
+++ b/tests/Server/TextDocument/References/GlobalTest.php
@@ -14,7 +14,11 @@ class GlobalTest extends ServerTestCase
         // class TestClass implements TestInterface
         // Get references for TestClass
         $definition = $this->getDefinitionLocation('TestClass');
-        $result = $this->textDocument->references(new ReferenceContext, new TextDocumentIdentifier($definition->uri), $definition->range->start);
+        $result = $this->textDocument->references(
+            new ReferenceContext,
+            new TextDocumentIdentifier($definition->uri),
+            $definition->range->start
+        )->wait();
         $this->assertEquals($this->getReferenceLocations('TestClass'), $result);
     }
 
@@ -23,7 +27,11 @@ class GlobalTest extends ServerTestCase
         // const TEST_CLASS_CONST = 123;
         // Get references for TEST_CLASS_CONST
         $definition = $this->getDefinitionLocation('TestClass::TEST_CLASS_CONST');
-        $result = $this->textDocument->references(new ReferenceContext, new TextDocumentIdentifier($definition->uri), $definition->range->start);
+        $result = $this->textDocument->references(
+            new ReferenceContext,
+            new TextDocumentIdentifier($definition->uri),
+            $definition->range->start
+        )->wait();
         $this->assertEquals($this->getReferenceLocations('TestClass::TEST_CLASS_CONST'), $result);
     }
 
@@ -32,7 +40,11 @@ class GlobalTest extends ServerTestCase
         // const TEST_CONST = 123;
         // Get references for TEST_CONST
         $definition = $this->getDefinitionLocation('TEST_CONST');
-        $result = $this->textDocument->references(new ReferenceContext, new TextDocumentIdentifier($definition->uri), $definition->range->start);
+        $result = $this->textDocument->references(
+            new ReferenceContext,
+            new TextDocumentIdentifier($definition->uri),
+            $definition->range->start
+        )->wait();
         $this->assertEquals($this->getReferenceLocations('TEST_CONST'), $result);
     }
 
@@ -41,7 +53,11 @@ class GlobalTest extends ServerTestCase
         // public static function staticTestMethod()
         // Get references for staticTestMethod
         $definition = $this->getDefinitionLocation('TestClass::staticTestMethod()');
-        $result = $this->textDocument->references(new ReferenceContext, new TextDocumentIdentifier($definition->uri), $definition->range->start);
+        $result = $this->textDocument->references(
+            new ReferenceContext,
+            new TextDocumentIdentifier($definition->uri),
+            $definition->range->start
+        )->wait();
         $this->assertEquals($this->getReferenceLocations('TestClass::staticTestMethod()'), $result);
     }
 
@@ -50,7 +66,11 @@ class GlobalTest extends ServerTestCase
         // public static $staticTestProperty;
         // Get references for $staticTestProperty
         $definition = $this->getDefinitionLocation('TestClass::staticTestProperty');
-        $result = $this->textDocument->references(new ReferenceContext, new TextDocumentIdentifier($definition->uri), $definition->range->start);
+        $result = $this->textDocument->references(
+            new ReferenceContext,
+            new TextDocumentIdentifier($definition->uri),
+            $definition->range->start
+        )->wait();
         $this->assertEquals($this->getReferenceLocations('TestClass::staticTestProperty'), $result);
     }
 
@@ -59,7 +79,11 @@ class GlobalTest extends ServerTestCase
         // public function testMethod($testParameter)
         // Get references for testMethod
         $definition = $this->getDefinitionLocation('TestClass::testMethod()');
-        $result = $this->textDocument->references(new ReferenceContext, new TextDocumentIdentifier($definition->uri), $definition->range->start);
+        $result = $this->textDocument->references(
+            new ReferenceContext,
+            new TextDocumentIdentifier($definition->uri),
+            $definition->range->start
+        )->wait();
         $this->assertEquals($this->getReferenceLocations('TestClass::testMethod()'), $result);
     }
 
@@ -68,7 +92,11 @@ class GlobalTest extends ServerTestCase
         // public $testProperty;
         // Get references for testProperty
         $definition = $this->getDefinitionLocation('TestClass::testProperty');
-        $result = $this->textDocument->references(new ReferenceContext, new TextDocumentIdentifier($definition->uri), $definition->range->start);
+        $result = $this->textDocument->references(
+            new ReferenceContext,
+            new TextDocumentIdentifier($definition->uri),
+            $definition->range->start
+        )->wait();
         $this->assertEquals($this->getReferenceLocations('TestClass::testProperty'), $result);
     }
 
@@ -77,7 +105,11 @@ class GlobalTest extends ServerTestCase
         // $var = 123;
         // Get definition for $var
         $uri = pathToUri(realpath(__DIR__ . '/../../../../fixtures/references.php'));
-        $result = $this->textDocument->references(new ReferenceContext, new TextDocumentIdentifier($uri), new Position(12, 3));
+        $result = $this->textDocument->references(
+            new ReferenceContext,
+            new TextDocumentIdentifier($uri),
+            new Position(12, 3)
+        )->wait();
         $this->assertEquals([
             new Location($uri, new Range(new Position(12, 0), new Position(12, 4))),
             new Location($uri, new Range(new Position(13, 5), new Position(13, 9))),
@@ -90,7 +122,11 @@ class GlobalTest extends ServerTestCase
         // function whatever(TestClass $param): TestClass
         // Get references for $param
         $uri = pathToUri(realpath(__DIR__ . '/../../../../fixtures/references.php'));
-        $result = $this->textDocument->references(new ReferenceContext, new TextDocumentIdentifier($uri), new Position(21, 32));
+        $result = $this->textDocument->references(
+            new ReferenceContext,
+            new TextDocumentIdentifier($uri),
+            new Position(21, 32)
+        )->wait();
         $this->assertEquals([new Location($uri, new Range(new Position(22, 9), new Position(22, 15)))], $result);
     }
 
@@ -100,7 +136,11 @@ class GlobalTest extends ServerTestCase
         // Get references for test_function
         $referencesUri = pathToUri(realpath(__DIR__ . '/../../../../fixtures/references.php'));
         $symbolsUri    = pathToUri(realpath(__DIR__ . '/../../../../fixtures/symbols.php'));
-        $result = $this->textDocument->references(new ReferenceContext, new TextDocumentIdentifier($symbolsUri), new Position(78, 16));
+        $result = $this->textDocument->references(
+            new ReferenceContext,
+            new TextDocumentIdentifier($symbolsUri),
+            new Position(78, 16)
+        )->wait();
         $this->assertEquals([
             new Location($referencesUri, new Range(new Position(10, 0), new Position(10, 13))),
             new Location($referencesUri, new Range(new Position(31, 13), new Position(31, 40)))
diff --git a/tests/Utils/RecursiveFileSearchTest.php b/tests/Utils/RecursiveFileSearchTest.php
deleted file mode 100644
index 671ebb1..0000000
--- a/tests/Utils/RecursiveFileSearchTest.php
+++ /dev/null
@@ -1,21 +0,0 @@
-<?php
-declare(strict_types = 1);
-
-namespace LanguageServer\Tests\Utils;
-
-use PHPUnit\Framework\TestCase;
-
-class RecursiveFileSearchTest extends TestCase
-{
-    public function testFilesAreFound()
-    {
-        $path = realpath(__DIR__ . '/../../fixtures/recursive');
-        $files = \LanguageServer\findFilesRecursive($path, '/.+\.txt/');
-        sort($files);
-        $this->assertEquals([
-            $path . DIRECTORY_SEPARATOR . 'a.txt',
-            $path . DIRECTORY_SEPARATOR . 'search' . DIRECTORY_SEPARATOR . 'b.txt',
-            $path . DIRECTORY_SEPARATOR . 'search' . DIRECTORY_SEPARATOR . 'here' . DIRECTORY_SEPARATOR . 'c.txt',
-        ], $files);
-    }
-}