Bug 1712557 - [devtools] Test hitting breakpoints via a reload link. r=bomsy

I thought I would reused browser_dbg-navigation.js, but its doc-scripts.html
test page is too complex and doesn't reproduce the broken breakpoint.
So I'm still cleaning it up, but ended up introducing a new dedicated test and test page.

Note that I'm removing the toggleScopes call as it was most likely a workaround.
Test helpers assume that scopes are visible and timeout if the scopes don't get updated.

The added test now only fails without fission + with server target switching.

Differential Revision: https://phabricator.services.mozilla.com/D116811

devtools/client/debugger/test/mochitest/browser.ini

@@ -104,6 +104,7 @@ skip-if = true # bug 1607636
 [browser_dbg-keyboard-shortcuts.js]
 skip-if = os == "linux" # bug 1351952
 [browser_dbg-layout-changes.js]
+[browser_dbg-link-reload.js]
 [browser_dbg-log-events.js]
 [browser_dbg-log-point-mapping.js]
 [browser_dbg-log-points.js]

devtools/client/debugger/test/mochitest/browser_dbg-link-reload.js

@@ -0,0 +1,67 @@
+/* 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 reload via an href link, which refers to the same document.
+ * It seems to cause different codepath compared to F5.
+ */
+add_task(async function() {
+  // Disable bfcache for Fission for now.
+  // If Fission is disabled, the pref is no-op.
+  await SpecialPowers.pushPrefEnv({
+    set: [["fission.bfcacheInParent", false]],
+  });
+
+  const dbg = await initDebugger("doc-reload-link.html");
+  const {
+    selectors: { getSelectedSource, getIsPaused, getCurrentThread },
+    getState
+  } = dbg;
+ 
+  info("Add a breakpoint that will be hit on reload");
+  await addBreakpoint(dbg, "doc-reload-link.html", 3);
+
+  for(let i = 0; i < 5; i++) {
+    let onReloaded = waitForReload(dbg.commands);
+
+    info("Reload via a link, this causes special race condition different from F5");
+    await SpecialPowers.spawn(gBrowser.selectedBrowser, [], function () {
+      const reloadLink = content.document.querySelector("a");
+      reloadLink.click();
+    });
+
+    info("Wait for paused\n");
+    await waitForPaused(dbg);
+
+    info("Check paused location\n");
+    let source = findSource(dbg, "doc-reload-link.html");
+    assertPausedAtSourceAndLine(dbg, source.id, 3);
+
+    await resume(dbg);
+
+    info("Wait for completion of the page load");
+    // This help ensure that the page loaded correctly and prevent pending request at teardown
+    await onReloaded;
+  }
+});
+
+async function waitForReload(commands) {
+  let resolve;
+  const onReloaded = new Promise(r => (resolve = r));
+  const { resourceCommand } = commands;
+  const { DOCUMENT_EVENT } = resourceCommand.TYPES;
+  const onAvailable = resources => {
+    if (resources.find(resource => resource.name == "dom-complete")) {
+      resourceCommand.unwatchResources([DOCUMENT_EVENT], { onAvailable });
+      resolve();
+    }
+  };
+  // Wait for watchResources completion before reloading, otherwise we might miss the dom-complete event
+  // if watchResources is still pending while the reload already started and finished loading the document early.
+  await resourceCommand.watchResources([DOCUMENT_EVENT], {
+    onAvailable,
+    ignoreExistingResources: true,
+  });
+  return onReloaded;
+}

devtools/client/debugger/test/mochitest/browser_dbg-navigation.js

@@ -21,23 +21,23 @@ add_task(async function() {
     getState
   } = dbg;
  
+  info("Pause in the first document");
   invokeInTab("firstCall");
   await waitForPaused(dbg);
 
-  await waitForRequestsToSettle(dbg);
+  info("Navigate while being paused in the first document");
   await navigate(dbg, "doc-scripts.html", "simple1.js");
+
+  info("Set a breakpoint on the second document and pause on it");
   await selectSource(dbg, "simple1");
   await addBreakpoint(dbg, "simple1.js", 4);
   invokeInTab("main");
   await waitForPaused(dbg);
-  await waitForLoadedSource(dbg, "simple1");
-  toggleScopes(dbg);
-
-  assertPausedLocation(dbg);
+  let source = findSource(dbg, "simple1.js");
+  assertPausedAtSourceAndLine(dbg, source.id, 4);
   is(countSources(dbg), 5, "5 sources are loaded.");
 
   await waitForRequestsToSettle(dbg);
-  // this test is intermittent without this
   let onBreakpoint = waitForDispatch(dbg.store, "SET_BREAKPOINT");
   await navigate(dbg, "doc-scripts.html", ...SOURCES);
   await onBreakpoint
@@ -45,23 +45,20 @@ add_task(async function() {
   ok(!getIsPaused(getCurrentThread()), "Is not paused");
 
   await waitForRequestsToSettle(dbg);
-  // this test is intermittent without this
   onBreakpoint = waitForDispatch(dbg.store, "SET_BREAKPOINT");
   await navigate(dbg, "doc-scripts.html", ...SOURCES);
   await onBreakpoint
   is(countSources(dbg), 5, "5 sources are loaded.");
 
-  // Test that the current select source persists across reloads
+  info("Test that the current selected source persists across reloads");
   await selectSource(dbg, "long.js");
 
   await waitForRequestsToSettle(dbg);
-  // this test is intermittent without this
   onBreakpoint = waitForDispatch(dbg.store, "SET_BREAKPOINT");
   await reload(dbg, "long.js");
   await onBreakpoint
   await waitForSelectedSource(dbg, "long.js");
 
-  await waitForRequestsToSettle(dbg);
   ok(getSelectedSource().url.includes("long.js"), "Selected source is long.js");
 });
 

devtools/client/debugger/test/mochitest/examples/doc-reload-link.html

@@ -0,0 +1,5 @@
+<meta charset="UTF-8">
+<script>
+  dump("dump\n");
+</script>
+<a href="doc-reload-link.html">reload via link</a>

devtools/client/debugger/test/mochitest/helpers.js

@@ -399,7 +399,7 @@ function assertPausedAtSourceAndLine(dbg, expectedSourceId, expectedLine) {
   const frames = dbg.selectors.getCurrentThreadFrames();
   ok(frames.length >= 1, "Got at least one frame");
   const { sourceId, line } = frames[0].location;
-  ok(sourceId == expectedSourceId, "Frame has correct source");
+  is(sourceId, expectedSourceId, "Frame has correct source");
   ok(
     line == expectedLine,
     `Frame paused at ${line}, but expected ${expectedLine}`