Barrett Cook

Unit Testing Controllers

13 August 2013

It all started with a one line bug fix. This line, to be precise:

-        if($basicInfo['enable_school_info']){
+        if($basicInfo['enable_school_info'] && $pageView !== self::PRIVATE_VIEW){

This change lived in /cool/www/mobile/profile.html, where school information was showing up on mobile private profile pages, and it was virtually untestable.

Background

Our controller code in /cool/www/ consists of *.html files. We leverage Apache as a router to look up the right file and execute it. Secretly living inside each of these *.html files is PHP code which executes procedurally.

The Problem

Procedural PHP is incredibly difficult to unit test. It is possible, but requires some gnarly code like this:

<?php
public function test_mobile_profile_controller() {
  // Mock out dependencies
  $can_view_profile = new StaticMock('tag_privacy', 'can_view_profile', false); // Declare a private profile

  // Execute the procedural controller code and trap the output
  ob_start();
  require(BASE_DIR.'/cool/www/mobile/profile.html');
  $result = ob_get_clean();

  // Assert dependencies were called
  $this->assertNotContains('<span class="school_info">', $result); // What happens if the template changes?
  $this->assertTrue($can_view_profile->calledOnce());
}

Generally, each controller instantiates a new tag_page object which render()’s and outputs a template to stdout. This means we are not able to verify that the controller gathered the correct data. Instead, we are verifying that the template was rendered correctly. Imagine trying to $this->assertEquals() against the entire <html> content of a page. If the template changes, this unit test could start to fail. But all we care about is that we never send school info for a private profile.

The Breakthrough

By moving all of the mobile/profile.html code into a new PHP class, I was able to create a class method that could be called over and over again instead of having to require() the file. The breakthrough here is that I could use dependency injection to pass in a fake tag_page object and assert that certain attributes were set on it. Now if the template changes it will not break this test.

<?php
public function test_mobile_profile_controller() {
  // Mock out dependencies
  $can_view_profile = new StaticMock('tag_privacy', 'can_view_profile', false); // Declare a private profile
  $page = Phockito::mock('tag_page');
  $controller = new tag_controller_mobile($page);

  // Execute the controller code
  $result = $controller->profile();

  // Assert dependencies were called
  Phockito::verify($page, 0)->assign('schoolInfo', anything()); // Make sure assign was called zero (0) times with key 'schoolInfo'
  ...
  Phockito::verify($page)->render('/mobile/profile/profile.php');  // Make sure render() was called with the correct template
  $this->assertTrue($can_view_profile->calledOnce());
}

Suddenly our controller (mobile/profile.html) looks very small.

<?php
require_once '../include/config.php';

$page = new tag_page();
$controller = new tag_controller_mobile($page);
$controller->profile();

You can see the full code change in this pull request.