From 5ebc761cf3780d98b344fd421ba669b9c3c23e7d Mon Sep 17 00:00:00 2001
From: Jan Sorgalla <jsorgalla@gmail.com>
Date: Mon, 24 Oct 2016 13:31:01 +0200
Subject: [PATCH] Use done() if available when resolving foreign thenables

---
 src/functions.php                            |  6 +++++
 tests/FunctionResolveTest.php                | 14 ++++++++++++
 tests/fixtures/SimpleRejectedTestDonable.php | 23 ++++++++++++++++++++
 3 files changed, 43 insertions(+)
 create mode 100644 tests/fixtures/SimpleRejectedTestDonable.php

diff --git a/src/functions.php b/src/functions.php
index 5f55f2ea..c5fd69d1 100644
--- a/src/functions.php
+++ b/src/functions.php
@@ -15,6 +15,12 @@ function resolve($promiseOrValue = null)
             $canceller = [$promiseOrValue, 'cancel'];
         }
 
+        if (method_exists($promiseOrValue, 'done')) {
+            return new Promise(function ($resolve, $reject, $notify) use ($promiseOrValue) {
+                $promiseOrValue->done($resolve, $reject, $notify);
+            }, $canceller);
+        }
+
         return new Promise(function ($resolve, $reject, $notify) use ($promiseOrValue) {
             $promiseOrValue->then($resolve, $reject, $notify);
         }, $canceller);
diff --git a/tests/FunctionResolveTest.php b/tests/FunctionResolveTest.php
index 53126bc0..52605963 100644
--- a/tests/FunctionResolveTest.php
+++ b/tests/FunctionResolveTest.php
@@ -60,6 +60,20 @@ public function shouldResolveAThenable()
             );
     }
 
+    /** @test */
+    public function shouldResolveADonable()
+    {
+        $this->setExpectedException('\Exception', 'UnhandledRejectionException');
+
+        $exception = new \Exception('UnhandledRejectionException');
+
+        $donable = new SimpleRejectedTestDonable($exception);
+
+        resolve($donable)
+            ->then()
+            ->done();
+    }
+
     /** @test */
     public function shouldResolveACancellableThenable()
     {
diff --git a/tests/fixtures/SimpleRejectedTestDonable.php b/tests/fixtures/SimpleRejectedTestDonable.php
new file mode 100644
index 00000000..5eb0683a
--- /dev/null
+++ b/tests/fixtures/SimpleRejectedTestDonable.php
@@ -0,0 +1,23 @@
+<?php
+
+namespace React\Promise;
+
+class SimpleRejectedTestDonable
+{
+    private $exception;
+
+    public function __construct(\Exception $exception)
+    {
+        $this->exception = $exception;
+    }
+
+    public function then(callable $onFulfilled = null, callable $onRejected = null, callable $onProgress = null)
+    {
+        return new self($this->exception);
+    }
+
+    public function done(callable $onFulfilled = null, callable $onRejected = null, callable $onProgress = null)
+    {
+        throw $this->exception;
+    }
+}