1 files changed, 15 insertions, 0 deletions
diff --git a/testing/mochitest/tests/browser/browser_setup_runs_for_only_tests.js b/testing/mochitest/tests/browser/browser_setup_runs_for_only_tests.js
new file mode 100644
index 0000000000..d1b811b2d1
--- /dev/null
+++ b/testing/mochitest/tests/browser/browser_setup_runs_for_only_tests.js
@@ -0,0 +1,15 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+let someVar = 1;
+
+add_setup(() => {
+  someVar = 2;
+});
+
+/* eslint-disable mozilla/reject-addtask-only */
+add_task(() => {
+  is(someVar, 2, "Setup should have run, even though this is the only test.");
+}).only();