diff --git a/tests/phpunit/tests/admin/includes/ajax-actions/menuLocationsSave.php b/tests/phpunit/tests/admin/includes/ajax-actions/menuLocationsSave.php
new file mode 100644
index 0000000000000..12e1c2b67523b
--- /dev/null
+++ b/tests/phpunit/tests/admin/includes/ajax-actions/menuLocationsSave.php
@@ -0,0 +1,141 @@
+<?php
+
+/**
+ * Admin Ajax functions to be tested.
+ */
+require_once ABSPATH . 'wp-admin/includes/ajax-actions.php';
+
+/**
+ * Testing wp_ajax_menu_locations_save() functionality.
+ *
+ * @package WordPress
+ * @subpackage UnitTests
+ * @since 3.1.0
+ *
+ * @group ajax
+ *
+ * @covers ::wp_ajax_menu_locations_save
+ */
+class Tests_wp_ajax_menu_locations_save extends WP_Ajax_UnitTestCase {
+
+	/**
+	 * Administrator user ID.
+	 *
+	 * @var int
+	 */
+	protected static $admin_id;
+
+	/**
+	 * Subscriber user ID.
+	 *
+	 * @var int
+	 */
+	protected static $subscriber_id;
+
+	/**
+	 * Setup test fixtures.
+	 *
+	 * @param WP_UnitTest_Factory $factory
+	 */
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ): void {
+		self::$admin_id      = $factory->user->create( array( 'role' => 'administrator' ) );
+		self::$subscriber_id = $factory->user->create( array( 'role' => 'subscriber' ) );
+	}
+
+	/**
+	 * Tests successful saving of menu locations.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_menu_locations_save_success(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$menu_id = self::factory()->term->create(
+			array(
+				'name'     => 'Test Menu',
+				'taxonomy' => 'nav_menu',
+			)
+		);
+
+		$_POST = array(
+			'action'                     => 'menu-locations-save',
+			'menu-settings-column-nonce' => wp_create_nonce( 'add-menu_item' ),
+			'menu-locations'             => array(
+				'primary' => $menu_id,
+			),
+		);
+
+		try {
+			$this->_handleAjax( 'menu-locations-save' );
+		} catch ( WPAjaxDieStopException $e ) {
+			$this->assertSame( '1', $e->getMessage(), 'The AJAX response should be 1.' );
+		}
+
+		$locations = get_theme_mod( 'nav_menu_locations' );
+		$this->assertIsArray( $locations );
+		$this->assertSame( $menu_id, $locations['primary'] );
+	}
+
+	/**
+	 * Tests failure due to invalid nonce.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_menu_locations_save_invalid_nonce(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST = array(
+			'action'                     => 'menu-locations-save',
+			'menu-settings-column-nonce' => 'invalid-nonce',
+			'menu-locations'             => array(
+				'primary' => 1,
+			),
+		);
+
+		$this->expectException( WPAjaxDieStopException::class );
+		$this->expectExceptionMessage( '-1' );
+
+		$this->_handleAjax( 'menu-locations-save' );
+	}
+
+	/**
+	 * Tests failure due to missing menu-locations.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_menu_locations_save_missing_locations(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST = array(
+			'action'                     => 'menu-locations-save',
+			'menu-settings-column-nonce' => wp_create_nonce( 'add-menu_item' ),
+		);
+
+		$this->expectException( WPAjaxDieStopException::class );
+		$this->expectExceptionMessage( '0' );
+
+		$this->_handleAjax( 'menu-locations-save' );
+	}
+
+	/**
+	 * Tests failure due to insufficient permissions.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_menu_locations_save_insufficient_permissions(): void {
+		wp_set_current_user( self::$subscriber_id );
+
+		$_POST = array(
+			'action'                     => 'menu-locations-save',
+			'menu-settings-column-nonce' => wp_create_nonce( 'add-menu_item' ),
+			'menu-locations'             => array(
+				'primary' => 1,
+			),
+		);
+
+		$this->expectException( WPAjaxDieStopException::class );
+		$this->expectExceptionMessage( '-1' );
+
+		$this->_handleAjax( 'menu-locations-save' );
+	}
+}