How to use fixtures to set up and tear down test environments in PHPUnit?

In PHPUnit, fixtures are used to set up and tear down the test environment for each test case. This helps in ensuring that each test starts with a clean, consistent state, and also helps in reusing common setup and teardown code.

Here is how you can use fixtures to set up and tear down test environments in PHPUnit:

Create a new class that extends PHPUnit\Framework\TestCase. This will be the base class for your test cases.
Add setup() and teardown() methods to your test class. The setup() method will be called before each test case, and the teardown() method will be called after each test case.
Inside the setup() method, set up any necessary dependencies, objects or resources that are required for your test case. For example, you can create a new instance of the class under test or connect to a database.
Inside the teardown() method, clean up any resources that were created during the setup() method. This can include closing database connections or deleting temporary files.

Here is an example:

use PHPUnit\Framework\TestCase;

class MyTestClass extends TestCase
{
    // This method is called before each test case
    protected function setUp(): void
    {
        // Set up any dependencies or resources here
        $this->setUpDatabase();
        $this->createTestUsers();
    }

    // This method is called after each test case
    protected function tearDown(): void
    {
        // Clean up any resources here
        $this->deleteTestUsers();
        $this->tearDownDatabase();
    }

    // Helper methods for setup and teardown
    private function setUpDatabase()
    {
        // Connect to the database or set up in-memory database
    }

    private function tearDownDatabase()
    {
        // Disconnect from the database or tear down in-memory database
    }

    private function createTestUsers()
    {
        // Create test user accounts for the test cases
    }

    private function deleteTestUsers()
    {
        // Delete test user accounts after the test cases
    }

    // Test cases go here
    public function testSomething()
    {
        // Test case logic goes here
    }
}

With this setup, PHPUnit will automatically call the setup() method before each test case and the teardown() method after each test case, ensuring a clean and consistent test environment for each test.