add asssertion for session errors

src/Illuminate/Foundation/Testing/TestResponse.php

@@ -428,6 +428,32 @@ public function assertSessionHasAll(array $bindings)
         return $this;
     }
 
+    /**
+     * Assert that the session has the given errors.
+     *
+     * @param  string|array  $keys
+     * @param  mixed  $format
+     * @return $this
+     */
+    public function assertSessionHasErrors($keys = [], $format = null)
+    {
+        $this->assertSessionHas('errors');
+
+        $keys = (array) $keys;
+
+        $errors = app('session.store')->get('errors');
+
+        foreach ($keys as $key => $value) {
+            if (is_int($key)) {
+                PHPUnit::assertTrue($errors->has($value), "Session missing error: $value");
+            } else {
+                PHPUnit::assertContains($value, $errors->get($key, $format));
+            }
+        }
+
+        return $this;
+    }
+
     /**
      * Assert that the session does not have a given key.
      *