diff --git a/tests/phpunit/tests/functions/sendFrameOptionsHeader.php b/tests/phpunit/tests/functions/sendFrameOptionsHeader.php
new file mode 100644
index 0000000000000..2e9d7f1395491
--- /dev/null
+++ b/tests/phpunit/tests/functions/sendFrameOptionsHeader.php
@@ -0,0 +1,28 @@
+<?php
+
+/**
+ * Test send_frame_options_header().
+ *
+ * @runTestsInSeparateProcesses
+ * @preserveGlobalState disabled
+ *
+ * @group functions
+ *
+ * @covers ::send_frame_options_header
+ */
+class Tests_Functions_sendFrameOptionsHeader extends WP_UnitTestCase {
+
+	/**
+	 * @ticket 59851
+	 *
+	 * @requires function xdebug_get_headers
+	 */
+	public function test_send_frame_options_header_sends_expected_headers() {
+		send_frame_options_header();
+
+		$headers = xdebug_get_headers();
+
+		$this->assertContains( 'X-Frame-Options: SAMEORIGIN', $headers );
+		$this->assertContains( "Content-Security-Policy: frame-ancestors 'self';", $headers );
+	}
+}