1 files changed, 56 insertions, 0 deletions
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_alarms_replaces.js b/toolkit/components/extensions/test/xpcshell/test_ext_alarms_replaces.js
new file mode 100644
index 0000000000..0d7597fa5a
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_alarms_replaces.js
@@ -0,0 +1,56 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(async function test_duplicate_alarm_name_replaces_alarm() {
+  function backgroundScript() {
+    let count = 0;
+
+    browser.alarms.onAlarm.addListener(async alarm => {
+      browser.test.assertEq(
+        "replaced alarm",
+        alarm.name,
+        "Expected last alarm"
+      );
+      browser.test.assertEq(
+        0,
+        count++,
+        "duplicate named alarm replaced existing alarm"
+      );
+      let results = await browser.alarms.getAll();
+
+      // "replaced alarm" is expected to be replaced with a non-repeating
+      // alarm, so it should not appear in the list of alarms.
+      browser.test.assertEq(1, results.length, "exactly one alarms exists");
+      browser.test.assertEq(
+        "unrelated alarm",
+        results[0].name,
+        "remaining alarm has the expected name"
+      );
+
+      browser.test.notifyPass("alarm-duplicate");
+    });
+
+    // Alarm that is so far in the future that it is never triggered.
+    browser.alarms.create("unrelated alarm", { delayInMinutes: 60 });
+    // Alarm that repeats.
+    browser.alarms.create("replaced alarm", {
+      delayInMinutes: 1 / 60,
+      periodInMinutes: 1 / 60,
+    });
+    // Before the repeating alarm is triggered, it is immediately replaced with
+    // a non-repeating alarm.
+    browser.alarms.create("replaced alarm", { delayInMinutes: 3 / 60 });
+  }
+
+  let extension = ExtensionTestUtils.loadExtension({
+    background: `(${backgroundScript})()`,
+    manifest: {
+      permissions: ["alarms"],
+    },
+  });
+
+  await extension.startup();
+  await extension.awaitFinish("alarm-duplicate");
+  await extension.unload();
+});