Test Dependencies and Fixtures - PHPUnit Part 4

Test Dependencies in PHPUnit

Sometimes, you may want to make one test method dependent on another. This is useful when a test requires the output of a previous test to proceed.

Using @depends Annotation

In PHPUnit, dependencies between tests can be established using the @depends annotation.

Example:

<?php
use PHPUnit\Framework\TestCase;

class UserTest extends TestCase
{
    public function testUserCanBeCreated()
    {
        $user = new User("John Doe");
        $this->assertInstanceOf(User::class, $user);
        return $user;
    }

    /**
     * @depends testUserCanBeCreated
     */
    public function testUserHasDefaultRole(User $user)
    {
        $this->assertEquals("guest", $user->getRole());
    }
}

Here testUserHasDefaultRole(User $user) method gets $user value from the testUserCanBeCreated method and is dependent on the testUserCanBeCreated

Benefits of Test Dependencies:

• Ensures that a test runs only if the dependent test passes.
• Helps maintain logical test flows.
• Reduces redundant setup code in multiple test methods.

Fixtures in PHPUnit

Test fixtures ensure that each test starts with a known state. PHPUnit provides setUp() and tearDown() methods to manage the test state before and after each test.

Using setUp() and tearDown()

• setUp(): Runs before each test method.
• tearDown(): Runs after each test method to clean up resources.

Example:

<?php
use PHPUnit\Framework\TestCase;

class DatabaseTest extends TestCase
{
    protected $db;

    protected function setUp(): void
    {
        $this->db = new DatabaseConnection();
        $this->db->connect();
    }

    public function testDatabaseConnection()
    {
        $this->assertTrue($this->db->isConnected());
    }

    protected function tearDown(): void
    {
        $this->db->disconnect();
    }
}

Why Use Fixtures?

• Ensures a predictable and isolated test environment.
• Reduces duplication of setup code in multiple test methods.
• Cleans up resources after tests to prevent side effects.

Conclusion

This article explored PHPUnit test dependencies and how to use fixtures to manage test state. By leveraging @depends, setUp(), and tearDown(), you can write more structured and maintainable unit tests. Next, we will discuss handling exceptions and mocking dependencies in PHPUnit.