public function testAddActionRedirectsAfterValidPost()
{
    $postObject = new Post();

    $postServiceMock = $this->getMockBuilder('BlogServicePostServiceInterface')
        ->disableOriginalConstructor()->getMock();
    $postServiceMock->expects($this->once())->method('savePost')
        ->will($this->returnValue($postObject));

    $postFormMock = $this->getMockBuilder('BlogFormPostForm')
        ->disableOriginalConstructor()->getMock();
    $postFormMock->expects($this->once())->method('isValid')
        ->will($this->returnValue(true));
    $postFormMock->expects($this->once())->method('getData')
        ->will($this->returnValue($postObject));

    $serviceManager = $this->getApplicationServiceLocator();
    $serviceManager->setAllowOverride(true);
    $serviceManager->setService('BlogServicePostServiceInterface', $postServiceMock);
    $serviceManager->setService('BlogFormPostForm', $postFormMock);

    $postData = array(
        'id'  => '',
        'title' => 'My title',
        'text' => 'My text'
    );
    $this->dispatch('/blog/add', 'POST', $postData);
    $this->assertModuleName('Blog');
    $this->assertControllerName('BlogControllerWrite');   //Controller name was defined in the module.config.php
    $this->assertControllerClass('WriteController');
    $this->assertMatchedRouteName('blog/add');
    $this->assertResponseStatusCode(302);
    $this->assertRedirectTo('/blog');
}

$postFormMock->expects($this->once())->method('isValid')
        ->will($this->returnValue(false));

public function addAction()
{
    $request = $this->getRequest();
    if ($request->isPost()) {
        $this->postForm->setData($request->getPost());
        if ($this->postForm->isValid()) {
            try {   //TODO create private method?
                $this->postService->savePost($this->postForm->getData());

                return $this->redirect()->toRoute('blog');
            } catch (Exception $e) {
                die($e->getMessage());
                //TODO Some DB Error happened, log it and let the user know
            }
        }
    }

    return new ViewModel(array(
        'form' => $this->postForm
    ));
}