1 files changed, 27 insertions, 0 deletions
diff --git a/devtools/shared/tests/xpcshell/test_flatten.js b/devtools/shared/tests/xpcshell/test_flatten.js
new file mode 100644
index 0000000000..2e2a80a9d5
--- /dev/null
+++ b/devtools/shared/tests/xpcshell/test_flatten.js
@@ -0,0 +1,27 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+// Test ThreadSafeDevToolsUtils.flatten
+
+function run_test() {
+  const { flatten } = DevToolsUtils;
+
+  const flat = flatten([
+    ["a", "b", "c"],
+    ["d", "e", "f"],
+    ["g", "h", "i"],
+  ]);
+
+  equal(flat.length, 9);
+  equal(flat[0], "a");
+  equal(flat[1], "b");
+  equal(flat[2], "c");
+  equal(flat[3], "d");
+  equal(flat[4], "e");
+  equal(flat[5], "f");
+  equal(flat[6], "g");
+  equal(flat[7], "h");
+  equal(flat[8], "i");
+}