1 files changed, 74 insertions, 0 deletions
diff --git a/browser/components/sessionstore/test/browser_637020.js b/browser/components/sessionstore/test/browser_637020.js
new file mode 100644
index 0000000000..46bf062002
--- /dev/null
+++ b/browser/components/sessionstore/test/browser_637020.js
@@ -0,0 +1,74 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+const TEST_URL =
+  "http://mochi.test:8888/browser/browser/components/" +
+  "sessionstore/test/browser_637020_slow.sjs";
+
+const TEST_STATE = {
+  windows: [
+    {
+      tabs: [
+        { entries: [{ url: "about:mozilla", triggeringPrincipal_base64 }] },
+        { entries: [{ url: "about:robots", triggeringPrincipal_base64 }] },
+      ],
+    },
+    {
+      tabs: [
+        { entries: [{ url: TEST_URL, triggeringPrincipal_base64 }] },
+        { entries: [{ url: TEST_URL, triggeringPrincipal_base64 }] },
+      ],
+    },
+  ],
+};
+
+/**
+ * This test ensures that windows that have just been restored will be marked
+ * as dirty, otherwise _getCurrentState() might ignore them when collecting
+ * state for the first time and we'd just save them as empty objects.
+ *
+ * The dirty state acts as a cache to not collect data from all windows all the
+ * time, so at the beginning, each window must be dirty so that we collect
+ * their state at least once.
+ */
+
+add_task(async function test() {
+  // Wait until the new window has been opened.
+  let promiseWindow = new Promise(resolve => {
+    Services.obs.addObserver(function onOpened(subject) {
+      Services.obs.removeObserver(onOpened, "domwindowopened");
+      resolve(subject);
+    }, "domwindowopened");
+  });
+
+  // Set the new browser state that will
+  // restore a window with two slowly loading tabs.
+  let backupState = SessionStore.getBrowserState();
+  SessionStore.setBrowserState(JSON.stringify(TEST_STATE));
+  let win = await promiseWindow;
+  let restoring = promiseWindowRestoring(win);
+  let restored = promiseWindowRestored(win);
+  await restoring;
+  await restored;
+
+  // The window has now been opened. Check the state that is returned,
+  // this should come from the cache while the window isn't restored, yet.
+  info("the window has been opened");
+  checkWindows();
+
+  // The history has now been restored and the tabs are loading. The data must
+  // now come from the window, if it's correctly been marked as dirty before.
+  await new Promise(resolve => whenDelayedStartupFinished(win, resolve));
+  info("the delayed startup has finished");
+  checkWindows();
+
+  // Cleanup.
+  await BrowserTestUtils.closeWindow(win);
+  await promiseBrowserState(backupState);
+});
+
+function checkWindows() {
+  let state = JSON.parse(SessionStore.getBrowserState());
+  is(state.windows[0].tabs.length, 2, "first window has two tabs");
+  is(state.windows[1].tabs.length, 2, "second window has two tabs");
+}