1 files changed, 55 insertions, 0 deletions
diff --git a/devtools/client/debugger/test/mochitest/browser_dbg-merge-scopes.js b/devtools/client/debugger/test/mochitest/browser_dbg-merge-scopes.js
new file mode 100644
index 0000000000..7bed9fc9ea
--- /dev/null
+++ b/devtools/client/debugger/test/mochitest/browser_dbg-merge-scopes.js
@@ -0,0 +1,55 @@
+/* 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/>. */
+
+// Test that adjacent scopes are merged together as expected.
+
+"use strict";
+
+add_task(async function () {
+  const dbg = await initDebugger("doc-merge-scopes.html");
+
+  invokeInTab("run");
+  await waitForPaused(dbg, "doc-merge-scopes.html");
+
+  // Function body and function lexical scopes are merged together.
+  expectLabels(dbg, ["first", "<this>", "arguments", "x", "y", "z"]);
+
+  await resume(dbg);
+  await waitForPaused(dbg);
+
+  // Function body and inner lexical scopes are not merged together.
+  await toggleScopeNode(dbg, 4);
+  expectLabels(dbg, ["Block", "<this>", "y", "second", "arguments", "x"]);
+
+  await resume(dbg);
+  await waitForPaused(dbg);
+
+  // When there is a function body, function lexical, and inner lexical scope,
+  // the first two are merged together.
+  await toggleScopeNode(dbg, 4);
+  expectLabels(dbg, [
+    "Block",
+    "<this>",
+    "z",
+    "third",
+    "arguments",
+    "v",
+    "x",
+    "y",
+  ]);
+});
+
+function getLabel(dbg, index) {
+  return findElement(dbg, "scopeNode", index).innerText;
+}
+
+function expectLabels(dbg, array) {
+  for (let i = 0; i < array.length; i++) {
+    is(
+      getLabel(dbg, i + 1),
+      array[i],
+      `Correct label ${array[i]} for index ${i + 1}`
+    );
+  }
+}