1 files changed, 47 insertions, 0 deletions
diff --git a/testing/xpcshell/example/unit/prefs_test_common.js b/testing/xpcshell/example/unit/prefs_test_common.js
new file mode 100644
index 0000000000..e12d3d5298
--- /dev/null
+++ b/testing/xpcshell/example/unit/prefs_test_common.js
@@ -0,0 +1,47 @@
+/* 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 isValidPref(prefName) {
+  return Services.prefs.getPrefType(prefName) !== Services.prefs.PREF_INVALID;
+}
+
+// Check a pref that appears in testing/profiles/xpcshell/user.js
+// but NOT in StaticPrefList.yaml, modules/libpref/init/all.js
+function has_pref_from_xpcshell_user_js() {
+  return isValidPref("extensions.webextensions.warnings-as-errors");
+}
+
+// Test pref from xpcshell-with-prefs.ini
+function has_pref_from_manifest_defaults() {
+  return isValidPref("dummy.pref.from.test.manifest");
+}
+
+// Test pref set in xpcshell.ini and xpcshell-with-prefs.ini
+function has_pref_from_manifest_file_section() {
+  return isValidPref("dummy.pref.from.test.file");
+}
+
+function check_common_xpcshell_with_prefs() {
+  Assert.ok(
+    has_pref_from_xpcshell_user_js(),
+    "Should have pref from xpcshell's user.js"
+  );
+
+  Assert.ok(
+    has_pref_from_manifest_defaults(),
+    "Should have pref from DEFAULTS in xpcshell-with-prefs.ini"
+  );
+}
+
+function check_common_xpcshell_without_prefs() {
+  Assert.ok(
+    has_pref_from_xpcshell_user_js(),
+    "Should have pref from xpcshell's user.js"
+  );
+
+  Assert.ok(
+    !has_pref_from_manifest_defaults(),
+    "xpcshell.ini did not set any prefs in DEFAULTS"
+  );
+}