diff --git a/tests/phpunit/tests/admin/includes/ajax-actions/healthCheckBackgroundUpdates.php b/tests/phpunit/tests/admin/includes/ajax-actions/healthCheckBackgroundUpdates.php
new file mode 100644
index 0000000000000..2ceb7a175283f
--- /dev/null
+++ b/tests/phpunit/tests/admin/includes/ajax-actions/healthCheckBackgroundUpdates.php
@@ -0,0 +1,147 @@
+<?php
+
+/**
+ * Admin Ajax functions to be tested.
+ */
+require_once ABSPATH . 'wp-admin/includes/ajax-actions.php';
+
+/**
+ * Testing wp_ajax_health_check_background_updates() functionality.
+ *
+ * @package WordPress
+ * @subpackage UnitTests
+ * @since 5.2.0
+ *
+ * @group ajax
+ *
+ * @covers ::wp_ajax_health_check_background_updates
+ */
+class Tests_wp_ajax_health_check_background_updates extends WP_Ajax_UnitTestCase {
+
+	/**
+	 * Administrator user ID.
+	 *
+	 * @var int
+	 */
+	protected static $admin_id;
+
+	/**
+	 * Setup test fixtures.
+	 *
+	 * @param WP_UnitTest_Factory $factory
+	 */
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ): void {
+		self::$admin_id = $factory->user->create( array( 'role' => 'administrator' ) );
+
+		if ( is_multisite() ) {
+			grant_super_admin( self::$admin_id );
+		}
+	}
+
+	public function set_up(): void {
+		parent::set_up();
+		add_action( 'wp_ajax_health-check-background-updates', 'wp_ajax_health_check_background_updates', 1 );
+
+		// Hook into wp_die to prevent execution from stopping.
+		add_filter( 'wp_die_ajax_handler', array( $this, 'getDieHandler' ) );
+	}
+
+	public function tear_down(): void {
+		remove_filter( 'wp_die_ajax_handler', array( $this, 'getDieHandler' ) );
+		parent::tear_down();
+	}
+
+	/**
+	 * Returns our custom die handler.
+	 *
+	 * @return callable
+	 */
+	public function getDieHandler() {
+		return array( $this, 'dieHandler' );
+	}
+
+	/**
+	 * Custom die handler that throws an exception.
+	 *
+	 * @param string|WP_Error $message
+	 */
+	public function dieHandler( $message ) {
+		$this->_last_response .= ob_get_clean();
+
+		if ( '' === $this->_last_response ) {
+			if ( is_scalar( $message ) ) {
+				$this->_last_response = (string) $message;
+			} else {
+				$this->_last_response = '0';
+			}
+		}
+
+		if ( '-1' === $this->_last_response || ( is_int( $message ) && -1 === $message ) ) {
+			throw new WPAjaxDieStopException( $this->_last_response );
+		}
+
+		throw new WPAjaxDieContinueException( $this->_last_response );
+	}
+
+	/**
+	 * Tests success for wp_ajax_health_check_background_updates().
+	 *
+	 * @ticket 65252
+	 * @expectedIncorrectUsage wp_ajax_health_check_background_updates
+	 */
+	public function test_health_check_background_updates_success(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST['_ajax_nonce'] = wp_create_nonce( 'health-check-site-status' );
+
+		try {
+			$this->_handleAjax( 'health-check-background-updates' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+
+		$this->assertTrue( $response['success'], 'AJAX response should be successful' );
+		$this->assertArrayHasKey( 'label', $response['data'], 'Response data should contain a label' );
+		$this->assertArrayHasKey( 'status', $response['data'], 'Response data should contain a status' );
+	}
+
+	/**
+	 * Tests failure with invalid nonce for wp_ajax_health_check_background_updates().
+	 *
+	 * @ticket 65252
+	 * @expectedIncorrectUsage wp_ajax_health_check_background_updates
+	 */
+	public function test_health_check_background_updates_invalid_nonce(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST['_ajax_nonce'] = 'invalid-nonce';
+
+		$this->expectException( WPAjaxDieStopException::class );
+		$this->expectExceptionMessage( '-1' );
+
+		$this->_handleAjax( 'health-check-background-updates' );
+	}
+
+	/**
+	 * Tests failure with insufficient permissions for wp_ajax_health_check_background_updates().
+	 *
+	 * @ticket 65252
+	 * @expectedIncorrectUsage wp_ajax_health_check_background_updates
+	 */
+	public function test_health_check_background_updates_insufficient_permissions(): void {
+		$subscriber_id = self::factory()->user->create( array( 'role' => 'subscriber' ) );
+		wp_set_current_user( $subscriber_id );
+
+		$_POST['_ajax_nonce'] = wp_create_nonce( 'health-check-site-status' );
+
+		try {
+			$this->_handleAjax( 'health-check-background-updates' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+
+		$this->assertFalse( $response['success'], 'AJAX response should be unsuccessful' );
+	}
+}
diff --git a/tests/phpunit/tests/admin/includes/ajax-actions/healthCheckDotorgCommunication.php b/tests/phpunit/tests/admin/includes/ajax-actions/healthCheckDotorgCommunication.php
new file mode 100644
index 0000000000000..443b096c8e32f
--- /dev/null
+++ b/tests/phpunit/tests/admin/includes/ajax-actions/healthCheckDotorgCommunication.php
@@ -0,0 +1,147 @@
+<?php
+
+/**
+ * Admin Ajax functions to be tested.
+ */
+require_once ABSPATH . 'wp-admin/includes/ajax-actions.php';
+
+/**
+ * Testing wp_ajax_health_check_dotorg_communication() functionality.
+ *
+ * @package WordPress
+ * @subpackage UnitTests
+ * @since 5.2.0
+ *
+ * @group ajax
+ *
+ * @covers ::wp_ajax_health_check_dotorg_communication
+ */
+class Tests_wp_ajax_health_check_dotorg_communication extends WP_Ajax_UnitTestCase {
+
+	/**
+	 * Administrator user ID.
+	 *
+	 * @var int
+	 */
+	protected static $admin_id;
+
+	/**
+	 * Setup test fixtures.
+	 *
+	 * @param WP_UnitTest_Factory $factory
+	 */
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ): void {
+		self::$admin_id = $factory->user->create( array( 'role' => 'administrator' ) );
+
+		if ( is_multisite() ) {
+			grant_super_admin( self::$admin_id );
+		}
+	}
+
+	public function set_up(): void {
+		parent::set_up();
+		add_action( 'wp_ajax_health-check-dotorg-communication', 'wp_ajax_health_check_dotorg_communication', 1 );
+
+		// Hook into wp_die to prevent execution from stopping.
+		add_filter( 'wp_die_ajax_handler', array( $this, 'getDieHandler' ) );
+	}
+
+	public function tear_down(): void {
+		remove_filter( 'wp_die_ajax_handler', array( $this, 'getDieHandler' ) );
+		parent::tear_down();
+	}
+
+	/**
+	 * Returns our custom die handler.
+	 *
+	 * @return callable
+	 */
+	public function getDieHandler() {
+		return array( $this, 'dieHandler' );
+	}
+
+	/**
+	 * Custom die handler that throws an exception.
+	 *
+	 * @param string|WP_Error $message
+	 */
+	public function dieHandler( $message ) {
+		$this->_last_response .= ob_get_clean();
+
+		if ( '' === $this->_last_response ) {
+			if ( is_scalar( $message ) ) {
+				$this->_last_response = (string) $message;
+			} else {
+				$this->_last_response = '0';
+			}
+		}
+
+		if ( '-1' === $this->_last_response || ( is_int( $message ) && -1 === $message ) ) {
+			throw new WPAjaxDieStopException( $this->_last_response );
+		}
+
+		throw new WPAjaxDieContinueException( $this->_last_response );
+	}
+
+	/**
+	 * Tests success for wp_ajax_health_check_dotorg_communication().
+	 *
+	 * @ticket 65252
+	 * @expectedIncorrectUsage wp_ajax_health_check_dotorg_communication
+	 */
+	public function test_health_check_dotorg_communication_success(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST['_ajax_nonce'] = wp_create_nonce( 'health-check-site-status' );
+
+		try {
+			$this->_handleAjax( 'health-check-dotorg-communication' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+
+		$this->assertTrue( $response['success'], 'AJAX response should be successful' );
+		$this->assertArrayHasKey( 'label', $response['data'], 'Response data should contain a label' );
+		$this->assertArrayHasKey( 'status', $response['data'], 'Response data should contain a status' );
+	}
+
+	/**
+	 * Tests failure with invalid nonce for wp_ajax_health_check_dotorg_communication().
+	 *
+	 * @ticket 65252
+	 * @expectedIncorrectUsage wp_ajax_health_check_dotorg_communication
+	 */
+	public function test_health_check_dotorg_communication_invalid_nonce(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST['_ajax_nonce'] = 'invalid-nonce';
+
+		$this->expectException( WPAjaxDieStopException::class );
+		$this->expectExceptionMessage( '-1' );
+
+		$this->_handleAjax( 'health-check-dotorg-communication' );
+	}
+
+	/**
+	 * Tests failure with insufficient permissions for wp_ajax_health_check_dotorg_communication().
+	 *
+	 * @ticket 65252
+	 * @expectedIncorrectUsage wp_ajax_health_check_dotorg_communication
+	 */
+	public function test_health_check_dotorg_communication_insufficient_permissions(): void {
+		$subscriber_id = self::factory()->user->create( array( 'role' => 'subscriber' ) );
+		wp_set_current_user( $subscriber_id );
+
+		$_POST['_ajax_nonce'] = wp_create_nonce( 'health-check-site-status' );
+
+		try {
+			$this->_handleAjax( 'health-check-dotorg-communication' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+
+		$this->assertFalse( $response['success'], 'AJAX response should be unsuccessful' );
+	}
+}
diff --git a/tests/phpunit/tests/admin/includes/ajax-actions/healthCheckGetSizes.php b/tests/phpunit/tests/admin/includes/ajax-actions/healthCheckGetSizes.php
new file mode 100644
index 0000000000000..89f18c2ec21d3
--- /dev/null
+++ b/tests/phpunit/tests/admin/includes/ajax-actions/healthCheckGetSizes.php
@@ -0,0 +1,155 @@
+<?php
+
+/**
+ * Admin Ajax functions to be tested.
+ */
+require_once ABSPATH . 'wp-admin/includes/ajax-actions.php';
+
+/**
+ * Testing wp_ajax_health_check_get_sizes() functionality.
+ *
+ * @package WordPress
+ * @subpackage UnitTests
+ * @since 5.2.0
+ *
+ * @group ajax
+ *
+ * @covers ::wp_ajax_health_check_get_sizes
+ */
+class Tests_wp_ajax_health_check_get_sizes extends WP_Ajax_UnitTestCase {
+
+	/**
+	 * Administrator user ID.
+	 *
+	 * @var int
+	 */
+	protected static $admin_id;
+
+	/**
+	 * Setup test fixtures.
+	 *
+	 * @param WP_UnitTest_Factory $factory
+	 */
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ): void {
+		self::$admin_id = $factory->user->create( array( 'role' => 'administrator' ) );
+
+		if ( is_multisite() ) {
+			grant_super_admin( self::$admin_id );
+		}
+	}
+
+	public function set_up(): void {
+		parent::set_up();
+		add_action( 'wp_ajax_health-check-get-sizes', 'wp_ajax_health_check_get_sizes', 1 );
+
+		// Hook into wp_die to prevent execution from stopping.
+		add_filter( 'wp_die_ajax_handler', array( $this, 'getDieHandler' ) );
+	}
+
+	public function tear_down(): void {
+		remove_filter( 'wp_die_ajax_handler', array( $this, 'getDieHandler' ) );
+		parent::tear_down();
+	}
+
+	/**
+	 * Returns our custom die handler.
+	 *
+	 * @return callable
+	 */
+	public function getDieHandler() {
+		return array( $this, 'dieHandler' );
+	}
+
+	/**
+	 * Custom die handler that throws an exception.
+	 *
+	 * @param string|WP_Error $message
+	 */
+	public function dieHandler( $message ) {
+		$this->_last_response .= ob_get_clean();
+
+		if ( '' === $this->_last_response ) {
+			if ( is_scalar( $message ) ) {
+				$this->_last_response = (string) $message;
+			} else {
+				$this->_last_response = '0';
+			}
+		}
+
+		if ( '-1' === $this->_last_response || ( is_int( $message ) && -1 === $message ) ) {
+			throw new WPAjaxDieStopException( $this->_last_response );
+		}
+
+		throw new WPAjaxDieContinueException( $this->_last_response );
+	}
+
+	/**
+	 * Tests success for wp_ajax_health_check_get_sizes().
+	 *
+	 * @ticket 65252
+	 * @expectedIncorrectUsage wp_ajax_health_check_get_sizes
+	 * @expectedDeprecated WP_Debug_Data::get_sizes
+	 */
+	public function test_health_check_get_sizes_success(): void {
+		if ( is_multisite() ) {
+			$this->markTestSkipped( 'The get_sizes health check is not available on multisite.' );
+		}
+
+		wp_set_current_user( self::$admin_id );
+
+		$_POST['_ajax_nonce'] = wp_create_nonce( 'health-check-site-status-result' );
+
+		try {
+			$this->_handleAjax( 'health-check-get-sizes' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+
+		if ( isset( $response['data']['total_size']['debug'] ) && 'not available' === $response['data']['total_size']['debug'] ) {
+			$this->assertFalse( $response['success'], 'AJAX response should be unsuccessful when sizes are not available' );
+		} else {
+			$this->assertTrue( $response['success'], 'AJAX response should be successful' );
+		}
+		$this->assertIsArray( $response['data'], 'Response data should be an array' );
+	}
+
+	/**
+	 * Tests failure with invalid nonce for wp_ajax_health_check_get_sizes().
+	 *
+	 * @ticket 65252
+	 * @expectedIncorrectUsage wp_ajax_health_check_get_sizes
+	 */
+	public function test_health_check_get_sizes_invalid_nonce(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST['_ajax_nonce'] = 'invalid-nonce';
+
+		$this->expectException( WPAjaxDieStopException::class );
+		$this->expectExceptionMessage( '-1' );
+
+		$this->_handleAjax( 'health-check-get-sizes' );
+	}
+
+	/**
+	 * Tests failure with insufficient permissions for wp_ajax_health_check_get_sizes().
+	 *
+	 * @ticket 65252
+	 * @expectedIncorrectUsage wp_ajax_health_check_get_sizes
+	 */
+	public function test_health_check_get_sizes_insufficient_permissions(): void {
+		$subscriber_id = self::factory()->user->create( array( 'role' => 'subscriber' ) );
+		wp_set_current_user( $subscriber_id );
+
+		$_POST['_ajax_nonce'] = wp_create_nonce( 'health-check-site-status-result' );
+
+		try {
+			$this->_handleAjax( 'health-check-get-sizes' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+
+		$this->assertFalse( $response['success'], 'AJAX response should be unsuccessful' );
+	}
+}
diff --git a/tests/phpunit/tests/admin/includes/ajax-actions/healthCheckLoopbackRequests.php b/tests/phpunit/tests/admin/includes/ajax-actions/healthCheckLoopbackRequests.php
new file mode 100644
index 0000000000000..73275a2fef784
--- /dev/null
+++ b/tests/phpunit/tests/admin/includes/ajax-actions/healthCheckLoopbackRequests.php
@@ -0,0 +1,147 @@
+<?php
+
+/**
+ * Admin Ajax functions to be tested.
+ */
+require_once ABSPATH . 'wp-admin/includes/ajax-actions.php';
+
+/**
+ * Testing wp_ajax_health_check_loopback_requests() functionality.
+ *
+ * @package WordPress
+ * @subpackage UnitTests
+ * @since 5.2.0
+ *
+ * @group ajax
+ *
+ * @covers ::wp_ajax_health_check_loopback_requests
+ */
+class Tests_wp_ajax_health_check_loopback_requests extends WP_Ajax_UnitTestCase {
+
+	/**
+	 * Administrator user ID.
+	 *
+	 * @var int
+	 */
+	protected static $admin_id;
+
+	/**
+	 * Setup test fixtures.
+	 *
+	 * @param WP_UnitTest_Factory $factory
+	 */
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ): void {
+		self::$admin_id = $factory->user->create( array( 'role' => 'administrator' ) );
+
+		if ( is_multisite() ) {
+			grant_super_admin( self::$admin_id );
+		}
+	}
+
+	public function set_up(): void {
+		parent::set_up();
+		add_action( 'wp_ajax_health-check-loopback-requests', 'wp_ajax_health_check_loopback_requests', 1 );
+
+		// Hook into wp_die to prevent execution from stopping.
+		add_filter( 'wp_die_ajax_handler', array( $this, 'getDieHandler' ) );
+	}
+
+	public function tear_down(): void {
+		remove_filter( 'wp_die_ajax_handler', array( $this, 'getDieHandler' ) );
+		parent::tear_down();
+	}
+
+	/**
+	 * Returns our custom die handler.
+	 *
+	 * @return callable
+	 */
+	public function getDieHandler() {
+		return array( $this, 'dieHandler' );
+	}
+
+	/**
+	 * Custom die handler that throws an exception.
+	 *
+	 * @param string|WP_Error $message
+	 */
+	public function dieHandler( $message ) {
+		$this->_last_response .= ob_get_clean();
+
+		if ( '' === $this->_last_response ) {
+			if ( is_scalar( $message ) ) {
+				$this->_last_response = (string) $message;
+			} else {
+				$this->_last_response = '0';
+			}
+		}
+
+		if ( '-1' === $this->_last_response || ( is_int( $message ) && -1 === $message ) ) {
+			throw new WPAjaxDieStopException( $this->_last_response );
+		}
+
+		throw new WPAjaxDieContinueException( $this->_last_response );
+	}
+
+	/**
+	 * Tests success for wp_ajax_health_check_loopback_requests().
+	 *
+	 * @ticket 65252
+	 * @expectedIncorrectUsage wp_ajax_health_check_loopback_requests
+	 */
+	public function test_health_check_loopback_requests_success(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST['_ajax_nonce'] = wp_create_nonce( 'health-check-site-status' );
+
+		try {
+			$this->_handleAjax( 'health-check-loopback-requests' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+
+		$this->assertTrue( $response['success'], 'AJAX response should be successful' );
+		$this->assertArrayHasKey( 'label', $response['data'], 'Response data should contain a label' );
+		$this->assertArrayHasKey( 'status', $response['data'], 'Response data should contain a status' );
+	}
+
+	/**
+	 * Tests failure with invalid nonce for wp_ajax_health_check_loopback_requests().
+	 *
+	 * @ticket 65252
+	 * @expectedIncorrectUsage wp_ajax_health_check_loopback_requests
+	 */
+	public function test_health_check_loopback_requests_invalid_nonce(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST['_ajax_nonce'] = 'invalid-nonce';
+
+		$this->expectException( WPAjaxDieStopException::class );
+		$this->expectExceptionMessage( '-1' );
+
+		$this->_handleAjax( 'health-check-loopback-requests' );
+	}
+
+	/**
+	 * Tests failure with insufficient permissions for wp_ajax_health_check_loopback_requests().
+	 *
+	 * @ticket 65252
+	 * @expectedIncorrectUsage wp_ajax_health_check_loopback_requests
+	 */
+	public function test_health_check_loopback_requests_insufficient_permissions(): void {
+		$subscriber_id = self::factory()->user->create( array( 'role' => 'subscriber' ) );
+		wp_set_current_user( $subscriber_id );
+
+		$_POST['_ajax_nonce'] = wp_create_nonce( 'health-check-site-status' );
+
+		try {
+			$this->_handleAjax( 'health-check-loopback-requests' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+
+		$this->assertFalse( $response['success'], 'AJAX response should be unsuccessful' );
+	}
+}
diff --git a/tests/phpunit/tests/admin/includes/ajax-actions/healthCheckSiteStatusResult.php b/tests/phpunit/tests/admin/includes/ajax-actions/healthCheckSiteStatusResult.php
new file mode 100644
index 0000000000000..ab563ed125e2a
--- /dev/null
+++ b/tests/phpunit/tests/admin/includes/ajax-actions/healthCheckSiteStatusResult.php
@@ -0,0 +1,151 @@
+<?php
+
+/**
+ * Admin Ajax functions to be tested.
+ */
+require_once ABSPATH . 'wp-admin/includes/ajax-actions.php';
+
+/**
+ * Testing wp_ajax_health_check_site_status_result() functionality.
+ *
+ * @package WordPress
+ * @subpackage UnitTests
+ * @since 5.2.0
+ *
+ * @group ajax
+ *
+ * @covers ::wp_ajax_health_check_site_status_result
+ */
+class Tests_wp_ajax_health_check_site_status_result extends WP_Ajax_UnitTestCase {
+
+	/**
+	 * Administrator user ID.
+	 *
+	 * @var int
+	 */
+	protected static $admin_id;
+
+	/**
+	 * Setup test fixtures.
+	 *
+	 * @param WP_UnitTest_Factory $factory
+	 */
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ): void {
+		self::$admin_id = $factory->user->create( array( 'role' => 'administrator' ) );
+
+		if ( is_multisite() ) {
+			grant_super_admin( self::$admin_id );
+		}
+	}
+
+	public function set_up(): void {
+		parent::set_up();
+		add_action( 'wp_ajax_health-check-site-status-result', 'wp_ajax_health_check_site_status_result', 1 );
+
+		// Hook into wp_die to prevent execution from stopping.
+		add_filter( 'wp_die_ajax_handler', array( $this, 'getDieHandler' ) );
+	}
+
+	public function tear_down(): void {
+		remove_filter( 'wp_die_ajax_handler', array( $this, 'getDieHandler' ) );
+		parent::tear_down();
+	}
+
+	/**
+	 * Returns our custom die handler.
+	 *
+	 * @return callable
+	 */
+	public function getDieHandler() {
+		return array( $this, 'dieHandler' );
+	}
+
+	/**
+	 * Custom die handler that throws an exception.
+	 *
+	 * @param string|WP_Error $message
+	 */
+	public function dieHandler( $message ) {
+		$this->_last_response .= ob_get_clean();
+
+		if ( '' === $this->_last_response ) {
+			if ( is_scalar( $message ) ) {
+				$this->_last_response = (string) $message;
+			} else {
+				$this->_last_response = '0';
+			}
+		}
+
+		if ( '-1' === $this->_last_response || ( is_int( $message ) && -1 === $message ) ) {
+			throw new WPAjaxDieStopException( $this->_last_response );
+		}
+
+		throw new WPAjaxDieContinueException( $this->_last_response );
+	}
+
+	/**
+	 * Tests success for wp_ajax_health_check_site_status_result().
+	 *
+	 * @ticket 65252
+	 */
+	public function test_health_check_site_status_result_success(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST['_ajax_nonce'] = wp_create_nonce( 'health-check-site-status-result' );
+		$_POST['counts']      = array(
+			'good'        => 1,
+			'recommended' => 2,
+			'critical'    => 3,
+		);
+
+		try {
+			$this->_handleAjax( 'health-check-site-status-result' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+
+		$this->assertTrue( $response['success'], 'AJAX response should be successful' );
+
+		$transient = get_transient( 'health-check-site-status-result' );
+		$this->assertNotFalse( $transient, 'Transient should be set' );
+		$this->assertEquals( wp_json_encode( $_POST['counts'] ), $transient, 'Transient value should match POST data' );
+	}
+
+	/**
+	 * Tests failure with invalid nonce for wp_ajax_health_check_site_status_result().
+	 *
+	 * @ticket 65252
+	 */
+	public function test_health_check_site_status_result_invalid_nonce(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST['_ajax_nonce'] = 'invalid-nonce';
+
+		$this->expectException( WPAjaxDieStopException::class );
+		$this->expectExceptionMessage( '-1' );
+
+		$this->_handleAjax( 'health-check-site-status-result' );
+	}
+
+	/**
+	 * Tests failure with insufficient permissions for wp_ajax_health_check_site_status_result().
+	 *
+	 * @ticket 65252
+	 */
+	public function test_health_check_site_status_result_insufficient_permissions(): void {
+		$subscriber_id = self::factory()->user->create( array( 'role' => 'subscriber' ) );
+		wp_set_current_user( $subscriber_id );
+
+		$_POST['_ajax_nonce'] = wp_create_nonce( 'health-check-site-status-result' );
+
+		try {
+			$this->_handleAjax( 'health-check-site-status-result' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+
+		$this->assertFalse( $response['success'], 'AJAX response should be unsuccessful' );
+	}
+}
diff --git a/tests/phpunit/tests/admin/includes/ajax-actions/sendPasswordReset.php b/tests/phpunit/tests/admin/includes/ajax-actions/sendPasswordReset.php
new file mode 100644
index 0000000000000..fa862135f6177
--- /dev/null
+++ b/tests/phpunit/tests/admin/includes/ajax-actions/sendPasswordReset.php
@@ -0,0 +1,164 @@
+<?php
+
+/**
+ * Admin Ajax functions to be tested.
+ */
+require_once ABSPATH . 'wp-admin/includes/ajax-actions.php';
+
+/**
+ * Testing wp_ajax_send_password_reset() functionality.
+ *
+ * @package WordPress
+ * @subpackage UnitTests
+ * @since 5.7.0
+ *
+ * @group ajax
+ *
+ * @covers ::wp_ajax_send_password_reset
+ */
+class Tests_wp_ajax_send_password_reset extends WP_Ajax_UnitTestCase {
+
+	/**
+	 * Administrator user ID.
+	 *
+	 * @var int
+	 */
+	protected static $admin_id;
+
+	/**
+	 * Target user ID.
+	 *
+	 * @var int
+	 */
+	protected static $user_id;
+
+	/**
+	 * Setup test fixtures.
+	 *
+	 * @param WP_UnitTest_Factory $factory
+	 */
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ): void {
+		self::$admin_id = $factory->user->create( array( 'role' => 'administrator' ) );
+		self::$user_id  = $factory->user->create( array( 'role' => 'subscriber' ) );
+
+		if ( is_multisite() ) {
+			grant_super_admin( self::$admin_id );
+		}
+	}
+
+	public function set_up(): void {
+		parent::set_up();
+		add_action( 'wp_ajax_send-password-reset', 'wp_ajax_send_password_reset', 1 );
+
+		// Hook into wp_die to prevent execution from stopping.
+		add_filter( 'wp_die_ajax_handler', array( $this, 'getDieHandler' ) );
+
+		// Clear mock email.
+		reset_phpmailer_instance();
+	}
+
+	public function tear_down(): void {
+		remove_filter( 'wp_die_ajax_handler', array( $this, 'getDieHandler' ) );
+		parent::tear_down();
+	}
+
+	/**
+	 * Returns our custom die handler.
+	 *
+	 * @return callable
+	 */
+	public function getDieHandler() {
+		return array( $this, 'dieHandler' );
+	}
+
+	/**
+	 * Custom die handler that throws an exception.
+	 *
+	 * @param string|WP_Error $message
+	 */
+	public function dieHandler( $message ) {
+		$this->_last_response .= ob_get_clean();
+
+		if ( '' === $this->_last_response ) {
+			if ( is_scalar( $message ) ) {
+				$this->_last_response = (string) $message;
+			} else {
+				$this->_last_response = '0';
+			}
+		}
+
+		if ( '-1' === $this->_last_response || ( is_int( $message ) && -1 === $message ) ) {
+			throw new WPAjaxDieStopException( $this->_last_response );
+		}
+
+		throw new WPAjaxDieContinueException( $this->_last_response );
+	}
+
+	/**
+	 * Tests success for sending a password reset email.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_send_password_reset_success(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST['user_id'] = self::$user_id;
+		$_POST['nonce']   = wp_create_nonce( 'reset-password-for-' . self::$user_id );
+
+		try {
+			$this->_handleAjax( 'send-password-reset' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+		$user     = get_userdata( self::$user_id );
+
+		$this->assertTrue( $response['success'], 'AJAX response should be successful' );
+		$this->assertStringContainsString( sprintf( 'A password reset link was emailed to %s.', $user->display_name ), $response['data'] );
+
+		// Verify email was sent.
+		$mailer = tests_retrieve_phpmailer_instance();
+		$this->assertStringContainsString( 'Password Reset', $mailer->get_sent()->subject );
+		$this->assertEquals( $user->user_email, $mailer->get_sent()->to[0][0] );
+	}
+
+	/**
+	 * Tests failure with invalid nonce for wp_ajax_send_password_reset().
+	 *
+	 * @ticket 65252
+	 */
+	public function test_send_password_reset_invalid_nonce(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST['user_id'] = self::$user_id;
+		$_POST['nonce']   = 'invalid-nonce';
+
+		$this->expectException( WPAjaxDieStopException::class );
+		$this->expectExceptionMessage( '-1' );
+
+		$this->_handleAjax( 'send-password-reset' );
+	}
+
+	/**
+	 * Tests failure with insufficient permissions for wp_ajax_send_password_reset().
+	 *
+	 * @ticket 65252
+	 */
+	public function test_send_password_reset_insufficient_permissions(): void {
+		$subscriber_id = self::factory()->user->create( array( 'role' => 'subscriber' ) );
+		wp_set_current_user( $subscriber_id );
+
+		$_POST['user_id'] = self::$admin_id;
+		$_POST['nonce']   = wp_create_nonce( 'reset-password-for-' . self::$admin_id );
+
+		try {
+			$this->_handleAjax( 'send-password-reset' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+
+		$this->assertFalse( $response['success'], 'AJAX response should be unsuccessful' );
+		$this->assertEquals( 'Cannot send password reset, permission denied.', $response['data'] );
+	}
+}
diff --git a/tests/phpunit/tests/admin/includes/ajax-actions/toggleAutoUpdates.php b/tests/phpunit/tests/admin/includes/ajax-actions/toggleAutoUpdates.php
new file mode 100644
index 0000000000000..ad722ac6c32a0
--- /dev/null
+++ b/tests/phpunit/tests/admin/includes/ajax-actions/toggleAutoUpdates.php
@@ -0,0 +1,211 @@
+<?php
+
+/**
+ * Admin Ajax functions to be tested.
+ */
+require_once ABSPATH . 'wp-admin/includes/ajax-actions.php';
+
+/**
+ * Testing wp_ajax_toggle_auto_updates() functionality.
+ *
+ * @package WordPress
+ * @subpackage UnitTests
+ * @since 5.5.0
+ *
+ * @group ajax
+ *
+ * @covers ::wp_ajax_toggle_auto_updates
+ */
+class Tests_wp_ajax_toggle_auto_updates extends WP_Ajax_UnitTestCase {
+
+	/**
+	 * Administrator user ID.
+	 *
+	 * @var int
+	 */
+	protected static $admin_id;
+
+	/**
+	 * Setup test fixtures.
+	 *
+	 * @param WP_UnitTest_Factory $factory
+	 */
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ): void {
+		self::$admin_id = $factory->user->create( array( 'role' => 'administrator' ) );
+
+		if ( is_multisite() ) {
+			grant_super_admin( self::$admin_id );
+		}
+	}
+
+	public function set_up(): void {
+		parent::set_up();
+		add_action( 'wp_ajax_toggle-auto-updates', 'wp_ajax_toggle_auto_updates', 1 );
+
+		// Hook into wp_die to prevent execution from stopping.
+		add_filter( 'wp_die_ajax_handler', array( $this, 'getDieHandler' ) );
+	}
+
+	public function tear_down(): void {
+		remove_filter( 'wp_die_ajax_handler', array( $this, 'getDieHandler' ) );
+		parent::tear_down();
+	}
+
+	/**
+	 * Returns our custom die handler.
+	 *
+	 * @return callable
+	 */
+	public function getDieHandler() {
+		return array( $this, 'dieHandler' );
+	}
+
+	/**
+	 * Custom die handler that throws an exception.
+	 *
+	 * @param string|WP_Error $message
+	 */
+	public function dieHandler( $message ) {
+		$this->_last_response .= ob_get_clean();
+
+		if ( '' === $this->_last_response ) {
+			if ( is_scalar( $message ) ) {
+				$this->_last_response = (string) $message;
+			} else {
+				$this->_last_response = '0';
+			}
+		}
+
+		if ( '-1' === $this->_last_response || ( is_int( $message ) && -1 === $message ) ) {
+			throw new WPAjaxDieStopException( $this->_last_response );
+		}
+
+		throw new WPAjaxDieContinueException( $this->_last_response );
+	}
+
+	/**
+	 * Tests success for toggling plugin auto-updates.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_toggle_auto_updates_plugin_success(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$plugin               = 'hello.php'; // Standard WP plugin.
+		$_POST['_ajax_nonce'] = wp_create_nonce( 'updates' );
+		$_POST['type']        = 'plugin';
+		$_POST['asset']       = $plugin;
+		$_POST['state']       = 'enable';
+
+		try {
+			$this->_handleAjax( 'toggle-auto-updates' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+
+		$this->assertTrue( $response['success'], 'AJAX response should be successful' );
+		$this->assertContains( $plugin, get_site_option( 'auto_update_plugins', array() ), 'Plugin should be in auto-update list' );
+
+		// Now disable it.
+		$this->_last_response = '';
+		$_POST['state']       = 'disable';
+
+		try {
+			$this->_handleAjax( 'toggle-auto-updates' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+		$this->assertTrue( $response['success'], 'AJAX response should be successful' );
+		$this->assertNotContains( $plugin, get_site_option( 'auto_update_plugins', array() ), 'Plugin should not be in auto-update list' );
+	}
+
+	/**
+	 * Tests success for toggling theme auto-updates.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_toggle_auto_updates_theme_success(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$theme                = 'twentytwentyone';
+		$_POST['_ajax_nonce'] = wp_create_nonce( 'updates' );
+		$_POST['type']        = 'theme';
+		$_POST['asset']       = $theme;
+		$_POST['state']       = 'enable';
+
+		try {
+			$this->_handleAjax( 'toggle-auto-updates' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+
+		$this->assertTrue( $response['success'], 'AJAX response should be successful' );
+		$this->assertContains( $theme, get_site_option( 'auto_update_themes', array() ), 'Theme should be in auto-update list' );
+	}
+
+	/**
+	 * Tests failure with invalid nonce for wp_ajax_toggle_auto_updates().
+	 *
+	 * @ticket 65252
+	 */
+	public function test_toggle_auto_updates_invalid_nonce(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST['_ajax_nonce'] = 'invalid-nonce';
+
+		$this->expectException( WPAjaxDieStopException::class );
+		$this->expectExceptionMessage( '-1' );
+
+		$this->_handleAjax( 'toggle-auto-updates' );
+	}
+
+	/**
+	 * Tests failure with insufficient permissions for wp_ajax_toggle_auto_updates().
+	 *
+	 * @ticket 65252
+	 */
+	public function test_toggle_auto_updates_insufficient_permissions(): void {
+		$subscriber_id = self::factory()->user->create( array( 'role' => 'subscriber' ) );
+		wp_set_current_user( $subscriber_id );
+
+		$_POST['_ajax_nonce'] = wp_create_nonce( 'updates' );
+		$_POST['type']        = 'plugin';
+		$_POST['asset']       = 'hello.php';
+		$_POST['state']       = 'enable';
+
+		try {
+			$this->_handleAjax( 'toggle-auto-updates' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+
+		$this->assertFalse( $response['success'], 'AJAX response should be unsuccessful' );
+		$this->assertEquals( 'Sorry, you are not allowed to modify plugins.', $response['data']['error'] );
+	}
+
+	/**
+	 * Tests failure with missing parameters for wp_ajax_toggle_auto_updates().
+	 *
+	 * @ticket 65252
+	 */
+	public function test_toggle_auto_updates_missing_parameters(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST['_ajax_nonce'] = wp_create_nonce( 'updates' );
+		// Missing 'type', 'asset', 'state'.
+
+		try {
+			$this->_handleAjax( 'toggle-auto-updates' );
+		} catch ( WPAjaxDieContinueException $e ) {
+		}
+
+		$response = json_decode( $this->_last_response, true );
+
+		$this->assertFalse( $response['success'], 'AJAX response should be unsuccessful' );
+		$this->assertEquals( 'Invalid data. No selected item.', $response['data']['error'] );
+	}
+}