Unit testing in WordPress provides time-saving and infallible testing by checking code assumptions in an automated way. PHPUnit is a commonly used CLI tool for running and reporting WordPress unit tests. Effective unit tests should be isolated, readable, quick, and follow an Arrange, Act, Assert pattern where preconditions are set up, the code is invoked, and results are asserted to expected behavior.

1. Unit Testing in WordPress
WordSesh 3

2. Manual Testing
Time consuming
Error-prone
Single point of knowledge

4. Unit Testing
Time saving
Infallible
Knowledge in code

5. “A unit test is an automated piece of code that
invokes a unit of work in the system and then
checks a single assumption about the behavior
of that unit of work.”

6. Write code before tests

7. Write tests before code

9. PHPUnit
CLI tool that runs unit tests & reports their results.
Created by Sebastian Bergmann
Easy to install

10. Unit Tests Requirements
Each test should be able to run on its own (isolated)
Easy to read
Quick to execute
Self explaining function names

11. Unit Tests Requirements
Test classes should inherit from WP_UnitTestCase
(which inherits from PHPUnit_Framework_TestCase)
Test functions should start w/ test
(test_my_test_name)

12. –William C. Wake
“This test case fits a pattern I call ‘Arrange,
Act, Assert’: it sets up data, calls a method
under test, and then verifies that it worked as
expected.”

13. Arrange Act Assert
Easy to
- Read
- Follow
- Understand
- Maintain

14. Arrange
Arrange all necessary preconditions and inputs.

15. Act
Act on the object or method under test.

16. Assert
Assert that the expected results have occurred.

17. Assertion
assertEqual()
assertTrue()
assertNotNull()
assertContains()
assertGreaterThan()
https://phpunit.de/manual/3.7/en/writing-tests-for-
phpunit.html#writing-tests-for-phpunit.assertions

18. function test_get_single_role_by_user_query() {
// Arrange
$this->factory->user->create_many( 2,
array( 'role' => 'subscriber' ) );
// Act
$u_query = new WP_User_Query( array( 'role' => 'subscriber' ) );
// Assert
$this->assertEquals( 2, count( $u_query->get_results() ) );
}

19. function test_get_single_role_by_user_query() {
// Arrange
$this->factory->user->create_many( 2,
array( 'role' => 'subscriber' ) );
// Act
$u_query = new WP_User_Query( array( 'role' => 'subscriber' ) );
// Assert
$this->assertEquals( 2, count( $u_query->get_results() ) );
}

20. function test_get_single_role_by_user_query() {
// Arrange
$this->factory->user->create_many( 2,
array( 'role' => 'subscriber' ) );
// Act
$u_query = new WP_User_Query( array( 'role' => 'subscriber' ) );
// Assert
$this->assertEquals( 2, count( $u_query->get_results() ) );
}

21. function test_get_single_role_by_user_query() {
// Arrange
$this->factory->user->create_many( 2,
array( 'role' => 'subscriber' ) );
// Act
$u_query = new WP_User_Query( array( 'role' => 'subscriber' ) );
// Assert
$this->assertEquals( 2, count( $u_query->get_results() ) );
}

24. Tools

32. Barry Kooij
@CageNL
barrykooij.com