Clean up canceller function references when they are no longer needed

Author: clue

tests/DeferredTest.php

@@ -19,4 +19,41 @@ public function getPromiseTestAdapter(callable $canceller = null)
             'settle'  => [$d, 'resolve'],
         ]);
     }
+
+    /** @test */
+    public function shouldRejectWithoutCreatingGarbageCyclesIfCancellerRejectsWithException()
+    {
+        gc_collect_cycles();
+        $deferred = new Deferred(function ($resolve, $reject) {
+            $reject(new \Exception('foo'));
+        });
+        $deferred->promise()->cancel();
+        unset($deferred);
+
+        $this->assertSame(0, gc_collect_cycles());
+    }
+
+    /** @test */
+    public function shouldRejectWithoutCreatingGarbageCyclesIfParentCancellerRejectsWithException()
+    {
+        gc_collect_cycles();
+        $deferred = new Deferred(function ($resolve, $reject) {
+            $reject(new \Exception('foo'));
+        });
+        $deferred->promise()->then()->cancel();
+        unset($deferred);
+
+        $this->assertSame(0, gc_collect_cycles());
+    }
+
+    /** @test */
+    public function shouldRejectWithoutCreatingGarbageCyclesIfCancellerHoldsReferenceAndExplicitlyRejectWithException()
+    {
+        gc_collect_cycles();
+        $deferred = new Deferred(function () use (&$deferred) { });
+        $deferred->reject(new \Exception('foo'));
+        unset($deferred);
+
+        $this->assertSame(0, gc_collect_cycles());
+    }
 }

tests/PromiseTest.php

@@ -137,7 +137,6 @@ public function shouldRejectWithoutCreatingGarbageCyclesIfResolverThrowsExceptio
     public function shouldRejectWithoutCreatingGarbageCyclesIfCancellerWithReferenceThrowsException()
     {
         gc_collect_cycles();
-
         $promise = new Promise(function () {}, function () use (&$promise) {
             throw new \Exception('foo');
         });
@@ -155,11 +154,25 @@ public function shouldRejectWithoutCreatingGarbageCyclesIfCancellerWithReference
     public function shouldRejectWithoutCreatingGarbageCyclesIfResolverWithReferenceThrowsException()
     {
         gc_collect_cycles();
-
         $promise = new Promise(function () use (&$promise) {
             throw new \Exception('foo');
         });
+        unset($promise);
+
+        $this->assertSame(0, gc_collect_cycles());
+    }
 
+    /**
+     * @test
+     * @requires PHP 7
+     * @see self::shouldRejectWithoutCreatingGarbageCyclesIfCancellerWithReferenceThrowsException
+     */
+    public function shouldRejectWithoutCreatingGarbageCyclesIfCancellerHoldsReferenceAndResolverThrowsException()
+    {
+        gc_collect_cycles();
+        $promise = new Promise(function () {
+            throw new \Exception('foo');
+        }, function () use (&$promise) { });
         unset($promise);
 
         $this->assertSame(0, gc_collect_cycles());