diff --git a/tests/phpunit/tests/admin/includes/ajax-actions/deleteInactiveWidgets.php b/tests/phpunit/tests/admin/includes/ajax-actions/deleteInactiveWidgets.php
new file mode 100644
index 0000000000000..1430828be857c
--- /dev/null
+++ b/tests/phpunit/tests/admin/includes/ajax-actions/deleteInactiveWidgets.php
@@ -0,0 +1,148 @@
+<?php
+
+/**
+ * Admin Ajax functions to be tested.
+ */
+require_once ABSPATH . 'wp-admin/includes/ajax-actions.php';
+
+/**
+ * Testing wp_ajax_delete_inactive_widgets() functionality.
+ *
+ * @package WordPress
+ * @subpackage UnitTests
+ * @since 4.4.0
+ *
+ * @group ajax
+ *
+ * @covers ::wp_ajax_delete_inactive_widgets
+ */
+class Tests_wp_ajax_delete_inactive_widgets 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' ) );
+	}
+
+	/**
+	 * Set up the test fixture.
+	 * Override wp_die().
+	 */
+	public function set_up(): void {
+		parent::set_up();
+		add_filter( 'wp_die_ajax_handler', array( $this, 'getDieHandler' ), 1, 1 );
+	}
+
+	/**
+	 * Tear down the test fixture.
+	 */
+	public function tear_down(): void {
+		remove_filter( 'wp_die_ajax_handler', array( $this, 'getDieHandler' ), 1, 1 );
+		parent::tear_down();
+	}
+
+	/**
+	 * Return our callback handler
+	 *
+	 * @return callback
+	 */
+	public function getDieHandler() {
+		return array( $this, 'dieHandler' );
+	}
+
+	/**
+	 * Handler for wp_die()
+	 * Don't die, just throw an exception.
+	 *
+	 * @param string|WP_Error $message
+	 * @param string          $title
+	 * @param array           $args
+	 * @throws WPAjaxDieStopException
+	 */
+	public function dieHandler( $message, $title = '', $args = array() ) {
+		throw new WPAjaxDieStopException( (string) $message );
+	}
+
+	/**
+	 * Tests successful deletion of inactive widgets.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_delete_inactive_widgets_success(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$id_base  = 'test_widget';
+		$settings = array(
+			1               => array( 'title' => 'Widget 1' ),
+			2               => array( 'title' => 'Widget 2' ),
+			'array_version' => 3,
+		);
+		update_option( 'widget_' . $id_base, $settings );
+
+		$inactive_widgets = array( $id_base . '-1', $id_base . '-2' );
+		wp_set_sidebars_widgets( array( 'wp_inactive_widgets' => $inactive_widgets ) );
+
+		$_POST = array(
+			'action'                => 'delete-inactive-widgets',
+			'removeinactivewidgets' => wp_create_nonce( 'remove-inactive-widgets' ),
+		);
+
+		try {
+			$this->_handleAjax( 'delete-inactive-widgets' );
+		} catch ( WPAjaxDieStopException $e ) {
+		}
+
+		// The actual logic is tested in Tests_wp_delete_inactive_widgets.
+		// Here we just verify the wrapper executes without major error.
+		$this->assertTrue( true );
+	}
+
+	/**
+	 * Tests failure due to invalid nonce.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_delete_inactive_widgets_invalid_nonce(): void {
+		wp_set_current_user( self::$admin_id );
+
+		$_POST = array(
+			'action'                => 'delete-inactive-widgets',
+			'removeinactivewidgets' => 'invalid-nonce',
+		);
+
+		$this->expectException( WPAjaxDieStopException::class );
+		$this->expectExceptionMessage( '-1' );
+
+		wp_ajax_delete_inactive_widgets();
+	}
+
+	/**
+	 * Tests failure due to insufficient permissions.
+	 *
+	 * @ticket 65252
+	 */
+	public function test_delete_inactive_widgets_insufficient_permissions(): void {
+		$subscriber_id = self::factory()->user->create( array( 'role' => 'subscriber' ) );
+		wp_set_current_user( $subscriber_id );
+
+		$_POST = array(
+			'action'                => 'delete-inactive-widgets',
+			'removeinactivewidgets' => wp_create_nonce( 'remove-inactive-widgets' ),
+		);
+
+		$this->expectException( WPAjaxDieStopException::class );
+		$this->expectExceptionMessage( '-1' );
+
+		wp_ajax_delete_inactive_widgets();
+	}
+}