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-rw-r--r--modules/libpref/test/unit/test_warnings.js62
1 files changed, 62 insertions, 0 deletions
diff --git a/modules/libpref/test/unit/test_warnings.js b/modules/libpref/test/unit/test_warnings.js
new file mode 100644
index 0000000000..a6782f5c59
--- /dev/null
+++ b/modules/libpref/test/unit/test_warnings.js
@@ -0,0 +1,62 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+function makeBuffer(length) {
+ return new Array(length + 1).join("x");
+}
+
+/**
+ * @resolves |true| if execution proceeded without warning,
+ * |false| if there was a warning.
+ */
+function checkWarning(pref, buffer) {
+ return new Promise(resolve => {
+ let complete = false;
+ let listener = {
+ observe(event) {
+ let message = event.message;
+ if (
+ !(
+ message.startsWith("Warning: attempting to write") &&
+ message.includes(pref)
+ )
+ ) {
+ return;
+ }
+ if (complete) {
+ return;
+ }
+ complete = true;
+ info("Warning while setting " + pref);
+ Services.console.unregisterListener(listener);
+ resolve(true);
+ },
+ };
+ do_timeout(1000, function () {
+ if (complete) {
+ return;
+ }
+ complete = true;
+ info("No warning while setting " + pref);
+ Services.console.unregisterListener(listener);
+ resolve(false);
+ });
+ Services.console.registerListener(listener);
+ Services.prefs.setCharPref(pref, buffer);
+ });
+}
+
+add_task(async function () {
+ // Simple change, shouldn't cause a warning
+ info("Checking that a simple change doesn't cause a warning");
+ let buf = makeBuffer(100);
+ let warned = await checkWarning("string.accept", buf);
+ Assert.ok(!warned);
+
+ // Large change, should cause a warning
+ info("Checking that a large change causes a warning");
+ buf = makeBuffer(32 * 1024);
+ warned = await checkWarning("string.warn", buf);
+ Assert.ok(warned);
+});