1 files changed, 97 insertions, 0 deletions
diff --git a/devtools/client/debugger/test/mochitest/browser_dbg-expressions-thread.js b/devtools/client/debugger/test/mochitest/browser_dbg-expressions-thread.js
new file mode 100644
index 0000000000..2d4dc94c9a
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+++ b/devtools/client/debugger/test/mochitest/browser_dbg-expressions-thread.js
@@ -0,0 +1,97 @@
+/* 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 the watch expressions update when selecting a different thread in the thread panel.
+ */
+
+"use strict";
+
+const TEST_COM_URI = `${URL_ROOT_COM_SSL}examples/doc_dbg-fission-frame-sources.html`;
+const TEST_ORG_IFRAME_URI = `${URL_ROOT_ORG_SSL}examples/doc_dbg-fission-frame-sources-frame.html`;
+const DATA_URI = "data:text/html,<title>foo</title>";
+
+add_task(async function () {
+  // Load a test page with a remote frame and wait for both sources to be visible.
+  // simple1.js is imported by the main page. simple2.js comes from the frame.
+  const dbg = await initDebuggerWithAbsoluteURL(
+    TEST_COM_URI,
+    "simple1.js",
+    "simple2.js"
+  );
+
+  const threadsPaneEl = await waitForElementWithSelector(
+    dbg,
+    ".threads-pane .header-label"
+  );
+
+  await waitForElement(dbg, "threadsPaneItems");
+  const threadsEl = findAllElements(dbg, "threadsPaneItems");
+  is(threadsEl.length, 2, "There are two threads in the thread panel");
+  const [mainThreadEl, remoteThreadEl] = threadsEl;
+  is(
+    mainThreadEl.textContent,
+    "Main Thread",
+    "first thread displayed is the main thread"
+  );
+  is(
+    remoteThreadEl.textContent,
+    "Test remote frame sources",
+    "second thread displayed is the remote thread"
+  );
+
+  await addExpression(dbg, "document.location.href");
+
+  is(
+    getWatchExpressionValue(dbg, 1),
+    JSON.stringify(TEST_COM_URI),
+    "expression is evaluated on the expected thread"
+  );
+
+  info(
+    "Select the remote frame thread and check that the expression is updated"
+  );
+  let onExpressionsEvaluated = waitForDispatch(
+    dbg.store,
+    "EVALUATE_EXPRESSIONS"
+  );
+  remoteThreadEl.click();
+  await onExpressionsEvaluated;
+
+  is(
+    getWatchExpressionValue(dbg, 1),
+    JSON.stringify(TEST_ORG_IFRAME_URI),
+    "expression is evaluated on the remote origin thread"
+  );
+
+  info("Select the main thread again and check that the expression is updated");
+  onExpressionsEvaluated = waitForDispatch(dbg.store, "EVALUATE_EXPRESSIONS");
+  mainThreadEl.click();
+  await onExpressionsEvaluated;
+
+  is(
+    getWatchExpressionValue(dbg, 1),
+    JSON.stringify(TEST_COM_URI),
+    "expression is evaluated on the main thread again"
+  );
+
+  // close the threads pane so following test don't have it open
+  threadsPaneEl.click();
+
+  await navigateToAbsoluteURL(dbg, DATA_URI);
+
+  is(
+    getWatchExpressionValue(dbg, 1),
+    JSON.stringify(DATA_URI),
+    "The location.host expression is updated after a navigaiton"
+  );
+
+  await addExpression(dbg, "document.title");
+
+  is(
+    getWatchExpressionValue(dbg, 2),
+    `"foo"`,
+    "We can add expressions after a navigation"
+  );
+});