Tests: Add unit tests for get_next_posts_link() and get_previous_posts_link().

The tests ensure that the `next_posts_link_attributes` and `previous_posts_link_attributes` filters are applied correctly.

Follow-up to [1383], [5045], [8502], [9632], [55429].

Props geisthanen, mukesh27, costdev, audrasjb, SergeyBiryukov.
Fixes #55751.

git-svn-id: https://develop.svn.wordpress.org/trunk@55442 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/link/getNextPostsLink.php

@@ -0,0 +1,46 @@
+<?php
+
+/**
+ * Tests the `get_next_posts_link()` function.
+ *
+ * @since 6.2.0
+ *
+ * @group link
+ *
+ * @covers ::get_next_posts_link
+ */
+class Tests_Link_GetNextPostsLink extends WP_UnitTestCase {
+
+	/**
+	 * Creates posts before any tests run.
+	 *
+	 * @param WP_UnitTest_Factory $factory
+	 */
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ) {
+		global $wp_query, $paged;
+
+		$factory->post->create_many( 3 );
+		$paged    = 2;
+		$wp_query = new WP_Query(
+			array(
+				'post_type'      => 'post',
+				'posts_per_page' => 1,
+				'paged'          => $paged,
+			)
+		);
+	}
+
+	/**
+	 * Tests that the 'next_posts_link_attributes' filter is applied correctly.
+	 *
+	 * @ticket 55751
+	 */
+	public function test_get_next_posts_link_should_apply_next_posts_link_attributes_filter() {
+		$filter = new MockAction();
+		add_filter( 'next_posts_link_attributes', array( &$filter, 'filter' ) );
+
+		get_next_posts_link();
+
+		$this->assertSame( 1, $filter->get_call_count() );
+	}
+}

tests/phpunit/tests/link/getPreviousPostsLink.php

@@ -0,0 +1,46 @@
+<?php
+
+/**
+ * Tests the `get_previous_posts_link()` function.
+ *
+ * @since 6.2.0
+ *
+ * @group link
+ *
+ * @covers ::get_previous_posts_link
+ */
+class Tests_Link_GetPreviousPostsLink extends WP_UnitTestCase {
+
+	/**
+	 * Creates posts before any tests run.
+	 *
+	 * @param WP_UnitTest_Factory $factory
+	 */
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ) {
+		global $wp_query, $paged;
+
+		$factory->post->create_many( 3 );
+		$paged    = 2;
+		$wp_query = new WP_Query(
+			array(
+				'post_type'      => 'post',
+				'posts_per_page' => 1,
+				'paged'          => $paged,
+			)
+		);
+	}
+
+	/**
+	 * Tests that the 'previous_posts_link_attributes' filter is applied correctly.
+	 *
+	 * @ticket 55751
+	 */
+	public function test_get_previous_posts_link_should_apply_previous_posts_link_attributes_filter() {
+		$filter = new MockAction();
+		add_filter( 'previous_posts_link_attributes', array( &$filter, 'filter' ) );
+
+		get_previous_posts_link();
+
+		$this->assertSame( 1, $filter->get_call_count() );
+	}
+}

tests/phpunit/tests/link/getThePostsNavigation.php

@@ -1,7 +1,7 @@
 <?php
 
 /**
- * Tests get_the_posts_navigation function.
+ * Tests the `get_the_posts_navigation()` function.
  *
  * @since 6.2.0
  *