PHP Errors: the Test

class LoginTest extends TestCase {

    public function test_redirect() {
        // Establish the error handler with the expected message.
        $expected_error = 'Notice: Undefined variable: nada';
        $this->expected_errors($expected_error);

        // Call the function to be tested.
        $actual = some_procedure();

        // Make sure the error happened.
        $this->assertTrue($this->were_expected_errors_found(),
                "Expected error not found: '$expected_error'");

        // Check that the result matches.
        $this->assertEquals('Hello!', $actual);
    }
}