1 files changed, 35 insertions, 0 deletions
diff --git a/intl/l10n/test/test_missing_variables.js b/intl/l10n/test/test_missing_variables.js
new file mode 100644
index 0000000000..8c05f7f94f
--- /dev/null
+++ b/intl/l10n/test/test_missing_variables.js
@@ -0,0 +1,35 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Disable `xpc::IsInAutomation()` so that missing variables don't throw
+// errors.
+Services.prefs.setBoolPref(
+  "security.turn_off_all_security_so_that_viruses_can_take_over_this_computer",
+  false
+);
+
+/**
+ * The following test demonstrates crashing behavior.
+ */
+add_task(function test_missing_variables() {
+  const l10nReg = new L10nRegistry();
+
+  const fs = [
+    { path: "/localization/en-US/browser/test.ftl", source: "welcome-message = Welcome { $user }\n" }
+  ]
+  const locales = ["en-US"];
+  const source = L10nFileSource.createMock("test", "app", locales, "/localization/{locale}", fs);
+  l10nReg.registerSources([source]);
+  const l10n = new Localization(["/browser/test.ftl"], true, l10nReg, locales);
+
+  {
+    const [message] = l10n.formatValuesSync([{ id: "welcome-message", args: { user: "Greg" } }]);
+    equal(message, "Welcome Greg");
+  }
+
+  {
+    // This will crash in debug builds.
+    const [message] = l10n.formatValuesSync([{ id: "welcome-message" }]);
+    equal(message, "Welcome {$user}");
+  }
+});