diff --git a/tests/phpunit/tests/functions/addMagicQuotes.php b/tests/phpunit/tests/functions/addMagicQuotes.php
index 81e1f010cb..447a4e3d6d 100644
--- a/tests/phpunit/tests/functions/addMagicQuotes.php
+++ b/tests/phpunit/tests/functions/addMagicQuotes.php
@@ -3,6 +3,7 @@
 /**
  * @group formatting
  * @group functions.php
+ * @covers ::add_magic_quotes
  */
 class Tests_Functions_AddMagicQuotes extends WP_UnitTestCase {
 
diff --git a/tests/phpunit/tests/functions/allowedProtocols.php b/tests/phpunit/tests/functions/allowedProtocols.php
index ad80a6c855..8803bed8a2 100644
--- a/tests/phpunit/tests/functions/allowedProtocols.php
+++ b/tests/phpunit/tests/functions/allowedProtocols.php
@@ -3,6 +3,7 @@
 /**
  * @group formatting
  * @group functions.php
+ * @covers ::wp_allowed_protocols
  */
 class Tests_Functions_AllowedProtocols extends WP_UnitTestCase {
 
diff --git a/tests/phpunit/tests/functions/anonymization.php b/tests/phpunit/tests/functions/anonymization.php
index 786b4cd238..4d84383828 100644
--- a/tests/phpunit/tests/functions/anonymization.php
+++ b/tests/phpunit/tests/functions/anonymization.php
@@ -10,12 +10,14 @@
 /**
  * Class Tests_Functions_Anonymization.
  *
+ * @since 4.9.6
+ *
  * @group functions.php
  * @group privacy
- *
- * @since 4.9.6
+ * @covers ::wp_privacy_anonymize_data
  */
 class Tests_Functions_Anonymization extends WP_UnitTestCase {
+
 	/**
 	 * Test that wp_privacy_anonymize_ip() properly anonymizes all possible IP address formats.
 	 *
diff --git a/tests/phpunit/tests/functions/canonicalCharset.php b/tests/phpunit/tests/functions/canonicalCharset.php
index ac89b1ec08..891cb9e767 100644
--- a/tests/phpunit/tests/functions/canonicalCharset.php
+++ b/tests/phpunit/tests/functions/canonicalCharset.php
@@ -1,11 +1,13 @@
 <?php
 
-/*
+/**
  * Validate that badly named charsets always return the correct format for UTF-8 and ISO-8859-1.
  *
- *  @since 4.8.0
+ * @since 4.8.0
+ *
+ * @group functions.php
+ * @covers ::_canonical_charset
  */
-
 class Tests_Functions_CanonicalCharset extends WP_UnitTestCase {
 
 	public function test_utf_8_lower() {
@@ -50,6 +52,8 @@ class Tests_Functions_CanonicalCharset extends WP_UnitTestCase {
 
 	/**
 	 * @ticket 23688
+	 *
+	 * @covers ::get_option
 	 */
 	function test_update_option_blog_charset() {
 		$orig_blog_charset = get_option( 'blog_charset' );
diff --git a/tests/phpunit/tests/functions/cleanupHeaderComment.php b/tests/phpunit/tests/functions/cleanupHeaderComment.php
index d7557c8813..73fcc1ee78 100644
--- a/tests/phpunit/tests/functions/cleanupHeaderComment.php
+++ b/tests/phpunit/tests/functions/cleanupHeaderComment.php
@@ -1,16 +1,18 @@
 <?php
-/*
+/**
  * Test _cleanup_header_comment().
  *
- * @group functions.php
  * @ticket 8497
  * @ticket 38101
+ *
+ * @group functions.php
+ * @covers ::_cleanup_header_comment
  */
 class Tests_Functions_CleanupHeaderComment extends WP_UnitTestCase {
+
 	/**
 	 * Test cleanup header of header comment.
 	 *
-	 * @covers ::_cleanup_header_comment
 	 * @dataProvider data_cleanup_header_comment
 	 *
 	 * @param string $test_string
diff --git a/tests/phpunit/tests/functions/deprecated.php b/tests/phpunit/tests/functions/deprecated.php
index 758ab0228a..a9046742ad 100644
--- a/tests/phpunit/tests/functions/deprecated.php
+++ b/tests/phpunit/tests/functions/deprecated.php
@@ -3,10 +3,13 @@
 /**
  * Test cases for deprecated functions, arguments, and files
  *
- * @package    WordPress
+ * @package WordPress
  * @subpackage Unit Tests
- * @since      3.5.0
- * @group      deprecated
+ *
+ * @since 3.5.0
+ *
+ * @group functions.php
+ * @group deprecated
  */
 class Tests_Functions_Deprecated extends WP_UnitTestCase {
 
@@ -140,6 +143,8 @@ class Tests_Functions_Deprecated extends WP_UnitTestCase {
 	 *
 	 * @ticket 6821
 	 * @expectedDeprecated wp_save_image_file
+	 *
+	 * @covers ::wp_save_image_file
 	 */
 	public function test_wp_save_image_file_deprecated_with_gd_resource() {
 		if ( ! function_exists( 'imagejpeg' ) ) {
@@ -163,6 +168,8 @@ class Tests_Functions_Deprecated extends WP_UnitTestCase {
 	 * Tests that wp_save_image_file() doesn't have a deprecated argument when passed a WP_Image_Editor.
 	 *
 	 * @ticket 6821
+	 *
+	 * @covers ::wp_save_image_file
 	 */
 	public function test_wp_save_image_file_not_deprecated_with_wp_image_editor() {
 		if ( ! function_exists( 'imagejpeg' ) ) {
diff --git a/tests/phpunit/tests/functions/doEnclose.php b/tests/phpunit/tests/functions/doEnclose.php
index 720eb8c728..b308798f73 100644
--- a/tests/phpunit/tests/functions/doEnclose.php
+++ b/tests/phpunit/tests/functions/doEnclose.php
@@ -10,11 +10,11 @@
 /**
  * Tests_Functions_DoEnclose class.
  *
+ * @since 5.3.0
+ *
  * @group functions.php
  * @group post
  * @covers ::do_enclose
- *
- * @since 5.3.0
  */
 class Tests_Functions_DoEnclose extends WP_UnitTestCase {
 
@@ -253,7 +253,7 @@ class Tests_Functions_DoEnclose extends WP_UnitTestCase {
 	 * @since 5.3.0
 	 *
 	 * @param  int    $post_id Post ID.
-	 * @return string          All enclosure data for the given post.
+	 * @return string  All enclosure data for the given post.
 	 */
 	protected function get_enclosed_by_post_id( $post_id ) {
 		return implode( '', (array) get_post_meta( $post_id, 'enclosure', false ) );
diff --git a/tests/phpunit/tests/functions/getStatusHeaderDesc.php b/tests/phpunit/tests/functions/getStatusHeaderDesc.php
index 956eae880f..c8a73ea99d 100644
--- a/tests/phpunit/tests/functions/getStatusHeaderDesc.php
+++ b/tests/phpunit/tests/functions/getStatusHeaderDesc.php
@@ -6,6 +6,7 @@
  * @since 5.3.0
  *
  * @group functions.php
+ * @covers ::get_status_header_desc
  */
 class Tests_Functions_GetStatusHeaderDesc extends WP_UnitTestCase {
 
diff --git a/tests/phpunit/tests/functions/getWeekstartend.php b/tests/phpunit/tests/functions/getWeekstartend.php
index ee76275be6..3b162b8401 100644
--- a/tests/phpunit/tests/functions/getWeekstartend.php
+++ b/tests/phpunit/tests/functions/getWeekstartend.php
@@ -2,6 +2,7 @@
 
 /**
  * @group functions.php
+ * @covers ::get_weekstartend
  */
 class Tests_Functions_GetWeekstartend extends WP_UnitTestCase {
 
diff --git a/tests/phpunit/tests/functions/isNewDay.php b/tests/phpunit/tests/functions/isNewDay.php
index 0bc459d52c..3201717fe0 100644
--- a/tests/phpunit/tests/functions/isNewDay.php
+++ b/tests/phpunit/tests/functions/isNewDay.php
@@ -5,6 +5,7 @@
  * @since 5.2.0
  *
  * @group functions.php
+ * @covers ::is_new_day
  */
 class Tests_Functions_IsNewDate extends WP_UnitTestCase {
 
diff --git a/tests/phpunit/tests/functions/isSerializedString.php b/tests/phpunit/tests/functions/isSerializedString.php
index 9a6bb4f7d7..677bf6d591 100644
--- a/tests/phpunit/tests/functions/isSerializedString.php
+++ b/tests/phpunit/tests/functions/isSerializedString.php
@@ -3,8 +3,10 @@
 /**
  * Tests for `is_serialized_string()`.
  *
- * @group functions.php
  * @ticket 42870
+ *
+ * @group functions.php
+ * @covers ::is_serialized_string
  */
 class Tests_Functions_IsSerializedString extends WP_UnitTestCase {
 
diff --git a/tests/phpunit/tests/functions/listFiles.php b/tests/phpunit/tests/functions/listFiles.php
index d461e0c195..484ecd6230 100644
--- a/tests/phpunit/tests/functions/listFiles.php
+++ b/tests/phpunit/tests/functions/listFiles.php
@@ -4,8 +4,10 @@
  * Test list_files().
  *
  * @group functions.php
+ * @covers ::list_files
  */
 class Tests_Functions_ListFiles extends WP_UnitTestCase {
+
 	public function test_list_files_returns_a_list_of_files() {
 		$admin_files = list_files( ABSPATH . 'wp-admin/' );
 		$this->assertInternalType( 'array', $admin_files );
diff --git a/tests/phpunit/tests/functions/numberFormatI18n.php b/tests/phpunit/tests/functions/numberFormatI18n.php
index 803b8ec02c..c57405887d 100644
--- a/tests/phpunit/tests/functions/numberFormatI18n.php
+++ b/tests/phpunit/tests/functions/numberFormatI18n.php
@@ -5,8 +5,10 @@
  *
  * @group functions.php
  * @group i18n
+ * @covers ::number_format_i18n
  */
 class Tests_Functions_NumberFormatI18n extends WP_UnitTestCase {
+
 	public function test_should_fall_back_to_number_format_when_wp_locale_is_not_set() {
 		$locale               = clone $GLOBALS['wp_locale'];
 		$GLOBALS['wp_locale'] = null;
diff --git a/tests/phpunit/tests/functions/pluginBasename.php b/tests/phpunit/tests/functions/pluginBasename.php
index e664d8fbd6..d7f7bcd6a0 100644
--- a/tests/phpunit/tests/functions/pluginBasename.php
+++ b/tests/phpunit/tests/functions/pluginBasename.php
@@ -5,6 +5,7 @@
  *
  * @group functions.php
  * @group plugins
+ * @covers ::plugin_basename
  */
 class Tests_Functions_PluginBasename extends WP_UnitTestCase {
 
diff --git a/tests/phpunit/tests/functions/referer.php b/tests/phpunit/tests/functions/referer.php
index 148fe89888..a6a1aaed99 100644
--- a/tests/phpunit/tests/functions/referer.php
+++ b/tests/phpunit/tests/functions/referer.php
@@ -4,8 +4,11 @@
  * Test wp_get_referer().
  *
  * @group functions.php
+ * @covers ::wp_get_referer
+ * @covers ::wp_get_raw_referer
  */
 class Tests_Functions_Referer extends WP_UnitTestCase {
+
 	public function setUp() {
 		parent::setUp();
 
diff --git a/tests/phpunit/tests/functions/removeQueryArg.php b/tests/phpunit/tests/functions/removeQueryArg.php
index 3d53f881e0..b8130abe8d 100644
--- a/tests/phpunit/tests/functions/removeQueryArg.php
+++ b/tests/phpunit/tests/functions/removeQueryArg.php
@@ -2,8 +2,10 @@
 
 /**
  * @group functions.php
+ * @covers ::remove_query_arg
  */
 class Tests_Functions_RemoveQueryArg extends WP_UnitTestCase {
+
 	/**
 	 * @dataProvider remove_query_arg_provider
 	 */
diff --git a/tests/phpunit/tests/functions/sizeFormat.php b/tests/phpunit/tests/functions/sizeFormat.php
index 7d473f23b9..281db07f5d 100644
--- a/tests/phpunit/tests/functions/sizeFormat.php
+++ b/tests/phpunit/tests/functions/sizeFormat.php
@@ -3,10 +3,13 @@
 /**
  * Tests for size_format()
  *
- * @group functions.php
  * @ticket 36635
+ *
+ * @group functions.php
+ * @covers ::size_format
  */
 class Tests_Functions_SizeFormat extends WP_UnitTestCase {
+
 	public function _data_size_format() {
 		return array(
 			array( array(), 0, false ),
diff --git a/tests/phpunit/tests/functions/underscoreReturn.php b/tests/phpunit/tests/functions/underscoreReturn.php
index 40222633f8..4973c2d328 100644
--- a/tests/phpunit/tests/functions/underscoreReturn.php
+++ b/tests/phpunit/tests/functions/underscoreReturn.php
@@ -8,26 +8,44 @@
  */
 class Tests_Functions_UnderscoreReturn extends WP_UnitTestCase {
 
+	/**
+	 * @covers ::__return_true
+	 */
 	public function test__return_true() {
 		$this->assertTrue( __return_true() );
 	}
 
+	/**
+	 * @covers ::__return_false
+	 */
 	public function test__return_false() {
 		$this->assertFalse( __return_false() );
 	}
 
+	/**
+	 * @covers ::__return_zero
+	 */
 	public function test__return_zero() {
 		$this->assertSame( 0, __return_zero() );
 	}
 
+	/**
+	 * @covers ::__return_empty_array
+	 */
 	public function test__return_empty_array() {
 		$this->assertSame( array(), __return_empty_array() );
 	}
 
+	/**
+	 * @covers ::__return_null
+	 */
 	public function test__return_null() {
 		$this->assertNull( __return_null() );
 	}
 
+	/**
+	 * @covers ::__return_empty_string
+	 */
 	public function test__return_empty_string() {
 		$this->assertSame( '', __return_empty_string() );
 	}
diff --git a/tests/phpunit/tests/functions/wp.php b/tests/phpunit/tests/functions/wp.php
index 80654a8526..04df43b348 100644
--- a/tests/phpunit/tests/functions/wp.php
+++ b/tests/phpunit/tests/functions/wp.php
@@ -3,6 +3,7 @@
 /**
  * @group functions.php
  * @group query
+ * @covers ::wp
  */
 class Tests_Functions_WP extends WP_UnitTestCase {
 
diff --git a/tests/phpunit/tests/functions/wpArraySliceAssoc.php b/tests/phpunit/tests/functions/wpArraySliceAssoc.php
index 98afc785c9..f7ce7293a2 100644
--- a/tests/phpunit/tests/functions/wpArraySliceAssoc.php
+++ b/tests/phpunit/tests/functions/wpArraySliceAssoc.php
@@ -5,8 +5,8 @@
  *
  * @since 5.3.0
  *
- * @covers ::wp_array_slice_assoc
  * @group functions.php
+ * @covers ::wp_array_slice_assoc
  */
 class Tests_Functions_wpArraySliceAssoc extends WP_UnitTestCase {
 
diff --git a/tests/phpunit/tests/functions/wpAuthCheck.php b/tests/phpunit/tests/functions/wpAuthCheck.php
index a583d01606..f69ab9e183 100644
--- a/tests/phpunit/tests/functions/wpAuthCheck.php
+++ b/tests/phpunit/tests/functions/wpAuthCheck.php
@@ -4,6 +4,8 @@
  * Tests for the behavior of `wp_auth_check()`
  *
  * @group functions.php
+ * @covers ::is_user_logged_in
+ * @covers ::wp_auth_check
  */
 class Tests_Functions_wpAuthCheck extends WP_UnitTestCase {
 
diff --git a/tests/phpunit/tests/functions/wpGetArchives.php b/tests/phpunit/tests/functions/wpGetArchives.php
index 35d011921d..ec983abe7a 100644
--- a/tests/phpunit/tests/functions/wpGetArchives.php
+++ b/tests/phpunit/tests/functions/wpGetArchives.php
@@ -1,12 +1,9 @@
 <?php
-/*
-$defaults = array(
-	'type' => 'monthly', 'limit' => '',
-	'format' => 'html', 'before' => '',
-	'after' => '', 'show_post_count' => false,
-	'echo' => 1, 'order' => 'DESC',
-);
-*/
+
+/**
+ * @group functions.php
+ * @covers ::wp_get_archives
+ */
 class Tests_Functions_wpGetArchives extends WP_UnitTestCase {
 	protected static $post_ids;
 	protected $month_url;
diff --git a/tests/phpunit/tests/functions/wpGetMimeTypes.php b/tests/phpunit/tests/functions/wpGetMimeTypes.php
index 8188ecd518..46d2fdfc06 100644
--- a/tests/phpunit/tests/functions/wpGetMimeTypes.php
+++ b/tests/phpunit/tests/functions/wpGetMimeTypes.php
@@ -4,6 +4,7 @@
  * Test wp_get_mime_types().
  *
  * @group functions.php
+ * @covers ::wp_get_mime_types
  */
 class Tests_Functions_wpGetMimeTypes extends WP_UnitTestCase {
 
diff --git a/tests/phpunit/tests/functions/wpListFilter.php b/tests/phpunit/tests/functions/wpListFilter.php
index e347308804..24d43b504d 100644
--- a/tests/phpunit/tests/functions/wpListFilter.php
+++ b/tests/phpunit/tests/functions/wpListFilter.php
@@ -4,6 +4,8 @@
  * Test wp_filter_object_list(), wp_list_filter(), wp_list_pluck().
  *
  * @group functions.php
+ * @covers ::wp_filter_object_list
+ * @covers ::wp_list_pluck
  */
 class Tests_Functions_wpListFilter extends WP_UnitTestCase {
 	var $object_list = array();
@@ -317,7 +319,6 @@ class Tests_Functions_wpListFilter extends WP_UnitTestCase {
 		$this->assertArrayHasKey( 'baz', $list );
 	}
 
-
 	function test_filter_object_list_nested_array_and_field() {
 		$list = wp_filter_object_list( $this->object_list, array( 'field4' => array( 'blue' ) ), 'AND', 'name' );
 		$this->assertSame( array( 'baz' => 'baz' ), $list );
diff --git a/tests/phpunit/tests/functions/wpListUtil.php b/tests/phpunit/tests/functions/wpListUtil.php
index 82265845b9..69b32d95f4 100644
--- a/tests/phpunit/tests/functions/wpListUtil.php
+++ b/tests/phpunit/tests/functions/wpListUtil.php
@@ -155,6 +155,8 @@ class Tests_Functions_wpListUtil extends WP_UnitTestCase {
 	/**
 	 * @dataProvider data_test_wp_list_pluck
 	 *
+	 * @covers ::wp_list_pluck
+	 *
 	 * @param array      $list      List of objects or arrays.
 	 * @param int|string $field     Field from the object to place instead of the entire object
 	 * @param int|string $index_key Field from the object to use as keys for the new array.
@@ -359,6 +361,8 @@ class Tests_Functions_wpListUtil extends WP_UnitTestCase {
 	/**
 	 * @dataProvider data_test_wp_list_filter
 	 *
+	 * @covers ::wp_list_filter
+	 *
 	 * @param array  $list     An array of objects to filter.
 	 * @param array  $args     An array of key => value arguments to match
 	 *                         against each object.
@@ -686,6 +690,8 @@ class Tests_Functions_wpListUtil extends WP_UnitTestCase {
 	/**
 	 * @dataProvider data_test_wp_list_sort
 	 *
+	 * @covers ::wp_list_sort
+	 *
 	 * @param string|array $orderby Either the field name to order by or an array
 	 *                              of multiple orderby fields as $orderby => $order.
 	 * @param string       $order   Either 'ASC' or 'DESC'.
@@ -1011,6 +1017,8 @@ class Tests_Functions_wpListUtil extends WP_UnitTestCase {
 	/**
 	 * @dataProvider data_test_wp_list_sort_preserve_keys
 	 *
+	 * @covers ::wp_list_sort
+	 *
 	 * @param string|array $orderby Either the field name to order by or an array
 	 *                              of multiple orderby fields as $orderby => $order.
 	 * @param string       $order   Either 'ASC' or 'DESC'.
@@ -1019,6 +1027,9 @@ class Tests_Functions_wpListUtil extends WP_UnitTestCase {
 		$this->assertSame( $expected, wp_list_sort( $list, $orderby, $order, true ) );
 	}
 
+	/**
+	 * @covers WP_List_Util::get_input
+	 */
 	public function test_wp_list_util_get_input() {
 		$input = array( 'foo', 'bar' );
 		$util  = new WP_List_Util( $input );
@@ -1026,6 +1037,9 @@ class Tests_Functions_wpListUtil extends WP_UnitTestCase {
 		$this->assertSameSets( $input, $util->get_input() );
 	}
 
+	/**
+	 * @covers WP_List_Util::get_output
+	 */
 	public function test_wp_list_util_get_output_immediately() {
 		$input = array( 'foo', 'bar' );
 		$util  = new WP_List_Util( $input );
@@ -1033,6 +1047,9 @@ class Tests_Functions_wpListUtil extends WP_UnitTestCase {
 		$this->assertSameSets( $input, $util->get_output() );
 	}
 
+	/**
+	 * @covers WP_List_Util::get_output
+	 */
 	public function test_wp_list_util_get_output() {
 		$expected = array(
 			(object) array(
diff --git a/tests/phpunit/tests/functions/wpRemoteFopen.php b/tests/phpunit/tests/functions/wpRemoteFopen.php
index ce3d8f37dd..1a4fa19619 100644
--- a/tests/phpunit/tests/functions/wpRemoteFopen.php
+++ b/tests/phpunit/tests/functions/wpRemoteFopen.php
@@ -3,6 +3,7 @@
  * @group http
  * @group external-http
  * @group functions.php
+ * @covers ::wp_remote_fopen
  */
 class Tests_Functions_wpRemoteFopen extends WP_UnitTestCase {
 
diff --git a/tests/phpunit/tests/functions/wpValidateBoolean.php b/tests/phpunit/tests/functions/wpValidateBoolean.php
index 848bccf236..3bc2c20108 100644
--- a/tests/phpunit/tests/functions/wpValidateBoolean.php
+++ b/tests/phpunit/tests/functions/wpValidateBoolean.php
@@ -3,8 +3,8 @@
 /**
  * Tests the wp_validate_boolean function.
  *
- * @covers ::wp_validate_boolean
  * @group functions.php
+ * @covers ::wp_validate_boolean
  */
 class Tests_Functions_wpValidateBoolean extends WP_UnitTestCase {
 	/**
@@ -47,8 +47,8 @@ class Tests_Functions_wpValidateBoolean extends WP_UnitTestCase {
 	 *
 	 * @dataProvider data_provider
 	 *
-	 * @param mixed $test_value.
-	 * @param bool $expected.
+	 * @param mixed $test_value
+	 * @param bool $expected
 	 *
 	 * @ticket 30238
 	 * @ticket 39868