MockHandler - Add support to reset internal queue

docs/testing.rst

@@ -47,10 +47,20 @@ a response or exception by shifting return values off of a queue.
     echo $client->request('GET', '/')->getStatusCode();
     //> 202
 
+    // Reset the queue and queue up a new response
+    $mock->reset();
+
+    $mock->append(new Response(201));
+
+    // As the mock was reset, the new response is the 201 CREATED,
+    // instead of the previously queued RequestException
+    echo $client->request('GET', '/')->getStatusCode();
+    //> 201
+
+
 When no more responses are in the queue and a request is sent, an
 ``OutOfBoundsException`` is thrown.
 
-
 History Middleware
 ==================
 
@@ -68,9 +78,9 @@ history of the requests that were sent by a client.
     $container = [];
     $history = Middleware::history($container);
 
-    $handlerStack = HandlerStack::create(); 
+    $handlerStack = HandlerStack::create();
     // or $handlerStack = HandlerStack::create($mock); if using the Mock handler.
-    
+
     // Add the history middleware to the handler stack.
     $handlerStack->push($history);
 

src/Handler/MockHandler.php

@@ -175,6 +175,11 @@ public function count()
         return count($this->queue);
     }
 
+    public function reset()
+    {
+        $this->queue = [];
+    }
+
     private function invokeStats(
         RequestInterface $request,
         array $options,

tests/Handler/MockHandlerTest.php

@@ -221,4 +221,16 @@ public function testInvokesOnStatsFunctionForError()
         $this->assertNull($stats->getResponse());
         $this->assertSame($request, $stats->getRequest());
     }
+
+    public function testResetQueue()
+    {
+        $mock = new MockHandler([new Response(200), new Response(204)]);
+        $this->assertCount(2, $mock);
+
+        $mock->reset();
+        $this->assertEmpty($mock);
+
+        $mock->append(new Response(500));
+        $this->assertCount(1, $mock);
+    }
 }