Build/Test Tools: Implement use of the void solution.

> PHPUnit 8.0.0 introduced a `void` return type declaration to the "fixture" methods – `setUpBeforeClass()`, `setUp()`, `tearDown()` and `tearDownAfterClass()`. As the `void` return type was not introduced until PHP 7.1, this makes it more difficult to create cross-version compatible tests when using fixtures, due to signature mismatches.
>
> The `Yoast\PHPUnitPolyfills\TestCases\TestCase` overcomes the signature mismatch by having two versions. The correct one will be loaded depending on the PHPUnit version being used.
>
> When using this TestCase, if an individual test, or another TestCase which extends this TestCase, needs to overload any of the "fixture" methods, it should do so by using a snake_case variant of the original fixture method name, i.e. `set_up_before_class()`, `set_up()`, `assert_pre_conditions()`, `assert_post_conditions()`, `tear_down()`, and `tear_down_after_class()`.
>
> The snake_case methods will automatically be called by PHPUnit.
>
> > IMPORTANT: The snake_case methods should not call the PHPUnit parent, i.e. do not use `parent::setUp()` from within an overloaded `set_up()` method. If necessary, DO call `parent::set_up()`.

Reference: https://github.com/Yoast/PHPUnit-Polyfills#testcases

This commit renames all declared fixture methods, and calls to parent versions of those fixture methods, from camelCase to snake_case.

Follow-up to [51559-51567].

Props jrf, hellofromTonya, johnbillion, netweb, dd32, pputzer, SergeyBiryukov.
See #46149.

git-svn-id: https://develop.svn.wordpress.org/trunk@51568 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/option/multisite.php

@@ -12,16 +12,16 @@ if ( is_multisite() ) :
 	class Tests_Multisite_Option extends WP_UnitTestCase {
 		protected $suppress = false;
 
-		function setUp() {
+		function set_up() {
 			global $wpdb;
-			parent::setUp();
+			parent::set_up();
 			$this->suppress = $wpdb->suppress_errors();
 		}
 
-		function tearDown() {
+		function tear_down() {
 			global $wpdb;
 			$wpdb->suppress_errors( $this->suppress );
-			parent::tearDown();
+			parent::tear_down();
 		}
 
 		function test_from_same_site() {

tests/phpunit/tests/option/siteTransient.php

@@ -5,8 +5,8 @@
  */
 class Tests_Option_SiteTransient extends WP_UnitTestCase {
 
-	public function setUp() {
-		parent::setUp();
+	public function set_up() {
+		parent::set_up();
 
 		if ( wp_using_ext_object_cache() ) {
 			$this->markTestSkipped( 'Not testable with an external object cache.' );

tests/phpunit/tests/option/slashes.php

@@ -7,8 +7,8 @@
  */
 class Tests_Option_Slashes extends WP_UnitTestCase {
 
-	function setUp() {
-		parent::setUp();
+	function set_up() {
+		parent::set_up();
 
 		// It is important to test with both even and odd numbered slashes,
 		// as KSES does a strip-then-add slashes in some of its function calls.

tests/phpunit/tests/option/transient.php

@@ -5,8 +5,8 @@
  */
 class Tests_Option_Transient extends WP_UnitTestCase {
 
-	public function setUp() {
-		parent::setUp();
+	public function set_up() {
+		parent::set_up();
 
 		if ( wp_using_ext_object_cache() ) {
 			$this->markTestSkipped( 'Not testable with an external object cache.' );

tests/phpunit/tests/option/userSettings.php

@@ -2,8 +2,8 @@
 class Tests_User_Settings extends WP_UnitTestCase {
 	protected $user_id;
 
-	function setUp() {
-		parent::setUp();
+	function set_up() {
+		parent::set_up();
 
 		$this->user_id = self::factory()->user->create(
 			array(
@@ -14,10 +14,10 @@ class Tests_User_Settings extends WP_UnitTestCase {
 		wp_set_current_user( $this->user_id );
 	}
 
-	function tearDown() {
+	function tear_down() {
 		unset( $GLOBALS['_updated_user_settings'] );
 
-		parent::tearDown();
+		parent::tear_down();
 	}
 
 	function test_set_user_setting() {

tests/phpunit/tests/option/wpLoadAllOptions.php

@@ -7,9 +7,9 @@
 class Tests_Option_WP_Load_Alloptions extends WP_UnitTestCase {
 	protected $alloptions = null;
 
-	function tearDown() {
+	function tear_down() {
 		$this->alloptions = null;
-		parent::tearDown();
+		parent::tear_down();
 	}
 
 	function test_if_alloptions_is_cached() {