Throw UnexpectedValueException if Promise gets rejected with non-Exception

README.md

@@ -118,6 +118,8 @@ $result = Block\await($promise, $loop);
 Once the promise is resolved, this will return whatever the promise resolves to.
 
 Once the promise is rejected, this will throw whatever the promise rejected with.
+If the promise did not reject with an `Exception`, then this function will
+throw an `UnexpectedValueException` instead.
 
 ```php
 try {
@@ -185,6 +187,8 @@ be used to correlate the return array to the promises passed.
 
 If ANY promise fails to resolve, this will try to `cancel()` all
 remaining promises and throw an `Exception`.
+If the promise did not reject with an `Exception`, then this function will
+throw an `UnexpectedValueException` instead.
 
 If no $timeout is given and either promise stays pending, then this will
 potentially wait/block forever until the last promise is settled.

src/functions.php

@@ -28,6 +28,8 @@ function sleep($time, LoopInterface $loop)
  * Once the promise is resolved, this will return whatever the promise resolves to.
  *
  * Once the promise is rejected, this will throw whatever the promise rejected with.
+ * If the promise did not reject with an `Exception`, then this function will
+ * throw an `UnexpectedValueException` instead.
  *
  * If no $timeout is given and the promise stays pending, then this will
  * potentially wait/block forever until the promise is settled.
@@ -47,6 +49,7 @@ function await(PromiseInterface $promise, LoopInterface $loop, $timeout = null)
     $wait = true;
     $resolved = null;
     $exception = null;
+    $rejected = false;
 
     if ($timeout !== null) {
         $promise = Timer\timeout($promise, $timeout, $loop);
@@ -58,8 +61,9 @@ function ($c) use (&$resolved, &$wait, $loop) {
             $wait = false;
             $loop->stop();
         },
-        function ($error) use (&$exception, &$wait, $loop) {
+        function ($error) use (&$exception, &$rejected, &$wait, $loop) {
             $exception = $error;
+            $rejected = true;
             $wait = false;
             $loop->stop();
         }
@@ -69,7 +73,15 @@ function ($error) use (&$exception, &$wait, $loop) {
         $loop->run();
     }
 
-    if ($exception !== null) {
+    if ($rejected) {
+        if (!$exception instanceof \Exception) {
+            $exception = new \UnexpectedValueException(
+                'Promise rejected with unexpected value of type ' . (is_object(($exception) ? get_class($exception) : gettype($exception))),
+                0,
+                $exception instanceof \Throwable ? $exception : null
+            );
+        }
+
         throw $exception;
     }
 
@@ -139,6 +151,8 @@ function awaitAny(array $promises, LoopInterface $loop, $timeout = null)
  *
  * If ANY promise fails to resolve, this will try to cancel() all
  * remaining promises and throw an Exception.
+ * If the promise did not reject with an `Exception`, then this function will
+ * throw an `UnexpectedValueException` instead.
  *
  * If no $timeout is given and either promise stays pending, then this will
  * potentially wait/block forever until the last promise is settled.

tests/FunctionAwaitAllTest.php

@@ -32,6 +32,17 @@ public function testAwaitAllRejected()
         Block\awaitAll($all, $this->loop);
     }
 
+    public function testAwaitAllRejectedWithFalseWillWrapInUnexpectedValueException()
+    {
+        $all = array(
+            $this->createPromiseResolved(1),
+            Promise\reject(false)
+        );
+
+        $this->setExpectedException('UnexpectedValueException');
+        Block\awaitAll($all, $this->loop);
+    }
+
     public function testAwaitAllOnlyRejected()
     {
         $all = array(

tests/FunctionAwaitTest.php

@@ -14,6 +14,38 @@ public function testAwaitOneRejected()
         Block\await($promise, $this->loop);
     }
 
+    public function testAwaitOneRejectedWithFalseWillWrapInUnexpectedValueException()
+    {
+        $promise = Promise\reject(false);
+
+        $this->setExpectedException('UnexpectedValueException');
+        Block\await($promise, $this->loop);
+    }
+
+    public function testAwaitOneRejectedWithNullWillWrapInUnexpectedValueException()
+    {
+        $promise = Promise\reject(null);
+
+        $this->setExpectedException('UnexpectedValueException');
+        Block\await($promise, $this->loop);
+    }
+
+    /**
+     * @requires PHP 7
+     */
+    public function testAwaitOneRejectedWithPhp7ErrorWillWrapInUnexpectedValueExceptionWithPrevious()
+    {
+        $promise = Promise\reject(new Error('Test'));
+
+        try {
+            Block\await($promise, $this->loop);
+            $this->fail();
+        } catch (UnexpectedValueException $e) {
+            $this->assertInstanceOf('Throwable', $e->getPrevious());
+            $this->assertEquals('Test', $e->getPrevious()->getMessage());
+        }
+    }
+
     public function testAwaitOneResolved()
     {
         $promise = $this->createPromiseResolved(2);