Mock new methods on an existing mock

Author: mnapoli

README.md

@@ -35,47 +35,57 @@ Yuck!
 Here is how to write it with EasyMock:
 
 ```php
-$mock = EasyMock::mock('My\Class', array(
+$mock = EasyMock::mock('My\Class', [
     'sayHello' => 'Hello',
-));
+]);
 ```
 
 ### Features
 
 You can mock methods so that they return values:
 
 ```php
-$mock = EasyMock::mock('My\Class', array(
+$mock = EasyMock::mock('My\Class', [
     'sayHello' => 'Hello',
-));
+]);
 ```
 
 Or so that they use a callback:
 
 ```php
-$mock = EasyMock::mock('My\Class', array(
+$mock = EasyMock::mock('My\Class', [
     'sayHello' => function ($name) {
         return 'Hello ' . $name;
     },
-));
+]);
 ```
 
 You can also have methods throw exceptions by providing an `Exception` instance:
 
 ```php
-$mock = EasyMock::mock('My\Class', array(
+$mock = EasyMock::mock('My\Class', [
     'sayHello' => new \RuntimeException('Whoops'),
-));
+]);
+```
+
+It is possible to call the `mock()` method again on an existing mock:
+
+```php
+$mock = EasyMock::mock('My\Class');
+
+$mock = EasyMock::mock($mock, [
+    'sayHello' => 'Hello',
+]);
 ```
 
 ### What if?
 
 If you want to use assertions or other PHPUnit features, just do it:
 
 ```php
-$mock = EasyMock::mock('My\Class', array(
+$mock = EasyMock::mock('My\Class', [
     'sayHello' => 'hello',
-));
+]);
 
 $mock->expects($this->once())
     ->method('sayGoodbye')

src/EasyMock.php

@@ -4,7 +4,7 @@
 
 use PHPUnit_Framework_MockObject_Generator;
 use PHPUnit_Framework_MockObject_Matcher_AnyInvokedCount;
-use PHPUnit_Framework_MockObject_MockObject;
+use PHPUnit_Framework_MockObject_MockObject as MockObject;
 
 /**
  * Generates mock objects.
@@ -19,23 +19,18 @@ class EasyMock
      * Methods not specified in $methods will be mocked to return null (default PHPUnit behavior).
      * The class constructor will *not* be called.
      *
-     * @param string $classname The class to mock.
+     * @param string $classname The class to mock. Can also be an existing mock to mock new methods.
      * @param array  $methods   Array of values to return, indexed by the method name.
      *
-     * @return PHPUnit_Framework_MockObject_MockObject
+     * @return \PHPUnit_Framework_MockObject_MockObject
      */
     public static function mock($classname, array $methods = array())
     {
-        $mockGenerator = new PHPUnit_Framework_MockObject_Generator();
-
-        /** @var PHPUnit_Framework_MockObject_MockObject $mock */
-        $mock = $mockGenerator->getMock(
-            $classname,
-            array(),
-            array(),
-            '',
-            false
-        );
+        if ($classname instanceof MockObject) {
+            $mock = $classname;
+        } else {
+            $mock = self::createMock($classname);
+        }
 
         foreach ($methods as $method => $return) {
             self::mockMethod($mock, $method, $return);
@@ -44,7 +39,7 @@ public static function mock($classname, array $methods = array())
         return $mock;
     }
 
-    private static function mockMethod(PHPUnit_Framework_MockObject_MockObject $mock, $method, $return)
+    private static function mockMethod(MockObject $mock, $method, $return)
     {
         $methodAssertion = $mock->expects(new PHPUnit_Framework_MockObject_Matcher_AnyInvokedCount)
             ->method($method);
@@ -57,4 +52,21 @@ private static function mockMethod(PHPUnit_Framework_MockObject_MockObject $mock
             $methodAssertion->willReturn($return);
         }
     }
+
+    /**
+     * @param string $classname
+     * @return MockObject
+     */
+    private static function createMock($classname)
+    {
+        $mockGenerator = new PHPUnit_Framework_MockObject_Generator();
+
+        return $mockGenerator->getMock(
+            $classname,
+            array(),
+            array(),
+            '',
+            false
+        );
+    }
 }

tests/MockClassTest.php

@@ -88,4 +88,18 @@ public function should_mock_existing_method_to_throw_exception()
         ));
         $mock->foo();
     }
+
+    /**
+     * @test
+     */
+    public function should_mock_new_methods_on_existing_mock()
+    {
+        /** @var ClassFixture $mock */
+        $mock = EasyMock::mock('EasyMock\Test\Fixture\ClassFixture');
+        $mock = EasyMock::mock($mock, array(
+            'foo' => 'bar',
+        ));
+
+        $this->assertSame('bar', $mock->foo());
+    }
 }