1 files changed, 29 insertions, 0 deletions
diff --git a/js/xpconnect/tests/unit/test_generateQI.js b/js/xpconnect/tests/unit/test_generateQI.js
new file mode 100644
index 0000000000..d54ed53212
--- /dev/null
+++ b/js/xpconnect/tests/unit/test_generateQI.js
@@ -0,0 +1,29 @@
+"use strict";
+
+add_task(async function test_generateQI() {
+  function checkQI(interfaces, iface) {
+    let obj = {
+      QueryInterface: ChromeUtils.generateQI(interfaces),
+    };
+    equal(obj.QueryInterface(iface), obj,
+         `Correct return value for query to ${iface}`);
+  }
+
+  // Test success scenarios.
+  checkQI([], Ci.nsISupports);
+
+  checkQI([Ci.nsIPropertyBag, "nsIPropertyBag2"], Ci.nsIPropertyBag);
+  checkQI([Ci.nsIPropertyBag, "nsIPropertyBag2"], Ci.nsIPropertyBag2);
+
+  checkQI([Ci.nsIPropertyBag, "nsIPropertyBag2", "nsINotARealInterface"], Ci.nsIPropertyBag2);
+
+  // Non-IID values get stringified, and don't cause any errors as long
+  // as there isn't a non-IID property with the same name on Ci.
+  checkQI([Ci.nsIPropertyBag, "nsIPropertyBag2", null, Object], Ci.nsIPropertyBag2);
+
+  ChromeUtils.generateQI([])(Ci.nsISupports);
+
+  // Test failure scenarios.
+  Assert.throws(() => checkQI([], Ci.nsIPropertyBag),
+                e => e.result == Cr.NS_ERROR_NO_INTERFACE);
+});