Testing basics

An automated test is code that checks other code: it opens a page or calls a function and compares the result with the expected one. The test suite is run with one command after every change, and you see at once whether something broke. A CodeIgniter project already has PHPUnit — the program that runs tests — configured, and the tests themselves live in the tests folder.

The first test

Create the file tests/unit/BlogHelperTest.php by hand. It checks the reading_time() function from the lesson about helpers:

// tests/unit/BlogHelperTest.php
use CodeIgniter\Test\CIUnitTestCase;
 
class BlogHelperTest extends CIUnitTestCase
{
    public function testShortTextTakesOneMinute(): void
    {
        helper('blog');
 
        $this->assertSame('1 min read', reading_time('A short text'));
    }
}

The file and class name ends in Test, the method name starts with test. assertSame() compares the expected value with the actual one.

Running

vendor/bin/phpunit

On Windows the command is written as vendor\bin\phpunit. The terminal prints a dot for every passed test and a summary: OK (1 test, 1 assertion). If a check fails, the expected and actual values and the test line are shown.

Testing a page

The FeatureTestTrait trait lets you "open" a site address without a browser:

// tests/feature/HomeTest.php
use CodeIgniter\Test\CIUnitTestCase;
use CodeIgniter\Test\FeatureTestTrait;
 
class HomeTest extends CIUnitTestCase
{
    use FeatureTestTrait;
 
    public function testLoginPageOpens(): void
    {
        $result = $this->get('login');
 
        $result->assertStatus(200);
        $result->assertSee('Log in');
    }
}

The get() method performs a request to a route and returns the response. The test checks that the login page opens with the 200 code and contains the words "Log in".

A test with a database

Tests work with a separate database — the tests connection from app/Config/Database.php — so that real data is not touched. The DatabaseTestTrait trait runs the migrations before the tests:

// tests/database/PostModelTest.php
use App\Models\PostModel;
use CodeIgniter\Test\CIUnitTestCase;
use CodeIgniter\Test\DatabaseTestTrait;
 
class PostModelTest extends CIUnitTestCase
{
    use DatabaseTestTrait;
 
    protected $migrate = true;
    protected $refresh = true;
    protected $namespace = 'App';
 
    public function testInsertSavesPost(): void
    {
        model(PostModel::class)->insert(['title' => 'Test post', 'body' => 'Text']);
 
        $this->seeInDatabase('posts', ['title' => 'Test post']);
    }
}

$namespace = 'App' says the migrations are taken from the app folder. seeInDatabase() checks that the table has a row with these values. By default the test database is SQLite in memory, which needs the sqlite3 PHP extension.

What to test

Start with what is most costly to break: logging in, saving a post, protected pages. A good test checks one statement and does not depend on other tests.

Common mistake

Database tests must not be pointed at the working connection: the $refresh property rolls the migrations back and drops the tables before every test. Do not replace the tests group in app/Config/Database.php with the details of the main database. If you need MySQL, create a separate empty database for tests, for example blog_test.