Adding unit tests to an existing WordPress plugin

Test user links

The first thing I want to test is to make sure that the links a user sees in their profile with calendar feeds are correct. Specifically, we’re going to look at the get_subscribe_link function.

You can see the completed tests for this section here.

Let’s start by copying the default sample test file and renaming it to test-feed-links.php. I always like to create different files for the areas of the plugins I’m writing tests for, even if that means I have lots of files to deal with. It’s far easier to stay organized with clearly labelled files.

This plugin is a bit older and instantiates a global variable as it starts up. This allows us to call that global when in our setUp function so that we have access to the plugin code. We’ll also need to use the WordPress Factory to set up a new user so that we can test the links provided with that user. That means our setUp and tearDown functions should look like this.

public function setUp(){
parent::setUp();
// getting the plugin global
$this->plugin = $GLOBALS[‘wptt_ics_feeds’];
// make a fake user
$this->editor = new WP_User( $this->factory->user->create( array( ‘role’ => ‘editor’ ) ) );
}
public function tearDown(){
parent::tearDown();
wp_delete_user( $this->editor->ID, true );
}

Now we can get to writing a test for our feed links. We’ll write two different tests to test both situations that the link function can find itself in. First, we’ll test get_subscribe_link() without any arguments.

/**
* Tests base feed link without author
*/
public function test_base_feed_link(){
$feed_link = $this->plugin->get_subscribe_link();
$complete_link = site_url() . ‘/?feed=wptticsfeeds’;
$this->assertEquals( $feed_link, $complete_link, ‘The feed links are not equal’ );
}

The first thing the code above does is access our plugin instance as defined in the setUp function and call the get_subscribe_link() function. Next, I hard code the expected output of the function so that I have something to compare against. Finally, we use assertEquals to compare the two values.

With that done I can head back over to terminal and run the tests with the phpunit command. If my tests pass I’ll see something like the output below. If they don’t pass then I’ll get a big red warning, which means I need to figure out why they aren’t passing and fix the tests.

In this case, our tests passed and we can move on to testing the output of our link function if we pass in an author name. You can see this test below.

/**

* Tests feed link with author

*/

public function test_author_feed_link(){

$feed_link = $this->plugin->get_subscribe_link( array( ‘author’ => $this->editor->ID ) );

$complete_link = esc_url( site_url() . ‘/?feed=wptticsfeeds&wpttauthor=’. $this->editor->user_login );

$this->assertEquals( $feed_link, $complete_link, ‘The feed links with author are not equal’ );

}

Here we do almost the same thing as we did when we tested our link previously. The change is that we pass in the user we created with our setUp function and then test to make sure that this link comes out as expected with assertEquals.

Now, let’s move on to testing the custom filter inside the plugin.