Constants.md

Managing Constants

Some applications — especially WordPress — will use PHP constants for configuration that should not be edited directly through the UI.

Normally, a constant cannot be redefined or removed once defined; however, the runkit7 extension exposes functions to modify normally immutable constructs.

Methods

setConstant()

Define (or re-define) a constant for the duration of the test.

setConstant(string $key[, mixed $value = null]): self

This is a wrapper around PHP's runkit_constant_redefine() function.

Parameters

$key

The constant name.

$value

The scalar value to set for the constant. Default is null

Return values

This method will return the calling class, enabling multiple methods to be chained.

An AssertWell\PHPUnitGlobalState\Exceptions\RedefineException will be thrown if the given constant cannot be (re-)defined.

---

deleteConstant()

Delete a defined constant for a single test.

deleteConstant(string $key): self

Parameters

$key

The constant name.

Return values

This method will return the calling class, enabling multiple methods to be chained.

Examples

Overriding a constant for a single test

WordPress enables site owners to enable or disable its debug mode based on a boolean WP_DEBUG constant. Many plugins may find themselves altering their behavior based on the value of this constant, but this is typically difficult to test.

Imagine we're working on a WordPress plugin that has a debug_comment(string $message) template function that will print an HTML comment only if WP_DEBUG is true.

use AssertWell\PHPUnitGlobalState\Constants;
use WP_UnitTestCase;

class MyTestClass extends WP_UnitTestCase
{
    use Constants;

    /**
     * @test
     */
    public function a_debug_comment_should_be_shown_if_WP_DEBUG_is_true()
    {
        $this->setConstant('WP_DEBUG', true);

        $this->assertStringContainsString('Test comment', debug_comment('Test comment'));
    }

    /**
     * @test
     */
    public function a_debug_comment_should_not_be_shown_if_WP_DEBUG_is_false()
    {
        $this->setConstant('WP_DEBUG', false);

        $this->assertEmpty(debug_comment('Test comment'));
    }
}

Regardless of whether or not these tests pass, the WP_DEBUG constant will be restored to its initial value after each test method completes.