1 files changed, 36 insertions, 0 deletions
diff --git a/devtools/server/tests/xpcshell/test_listsources-02.js b/devtools/server/tests/xpcshell/test_listsources-02.js
new file mode 100644
index 0000000000..a2f9cc3bda
--- /dev/null
+++ b/devtools/server/tests/xpcshell/test_listsources-02.js
@@ -0,0 +1,36 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/**
+ * Check getting sources before there are any.
+ */
+
+var gNumTimesSourcesSent = 0;
+
+add_task(
+  threadFrontTest(async ({ threadFront, client }) => {
+    client.request = (function (origRequest) {
+      return function (request, onResponse) {
+        if (request.type === "sources") {
+          ++gNumTimesSourcesSent;
+        }
+        return origRequest.call(this, request, onResponse);
+      };
+    })(client.request);
+
+    // Test listing zero sources
+    const packet = await threadFront.getSources();
+
+    Assert.ok(!packet.error);
+    Assert.ok(!!packet.sources);
+    Assert.equal(packet.sources.length, 0);
+
+    Assert.ok(
+      gNumTimesSourcesSent <= 1,
+      "Should only send one sources request at most, even though we" +
+        " might have had to send one to determine feature support."
+    );
+  })
+);