Browser test for prerendering in general

chrome/browser/prerender/prerender_browsertest.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/command_line.h"
+#include "base/path_service.h"
+#include "chrome/browser/prerender/prerender_contents.h"
+#include "chrome/browser/prerender/prerender_manager.h"
+#include "chrome/browser/profiles/profile.h"
+#include "chrome/browser/tab_contents/tab_contents.h"
+#include "chrome/browser/ui/browser.h"
+#include "chrome/common/chrome_paths.h"
+#include "chrome/common/chrome_switches.h"
+#include "chrome/common/net/url_request_context_getter.h"
+#include "chrome/test/in_process_browser_test.h"
+#include "chrome/test/ui_test_utils.h"
+#include "net/url_request/url_request_context.h"
+
+/* Prerender tests work as follows:

[cbentzel, 2011/01/21 18:37:02]

I haven't really seen /* style commenting in Chrome - although style guide
allows it, // is far more common. 

[mmenke, 2011/01/21 20:12:20]

You're right.  Hadn't really thought about it.  Changed.

+ *
+ * A page with a prefetch link to the test page is loaded.  Once prerendered,
+ * its Javascript function DidPrerenderPass() is called, which returns true if
+ * the page behaves as expected when prerendered.
+ *
+ * The prerendered page is then displayed on a tab.  The Javascript function
+ * DidDisplayPass() is called, and returns true if the page behaved as it
+ * should while being displayed.
+ */
+
+namespace {
+
+// PrerenderContents that stops the UI message loop on DidStopLoading().
+class TestPrerenderContents : public PrerenderContents {
+ public:
+  TestPrerenderContents(
+      PrerenderManager* prerender_manager, Profile* profile, const GURL& url,
+      const std::vector<GURL>& alias_urls)
+      : PrerenderContents(prerender_manager, profile, url, alias_urls),
+        did_finish_loading_(false) {
+  }
+
+  virtual void DidStopLoading() {
+    PrerenderContents::DidStopLoading();
+    did_finish_loading_ = true;
+    MessageLoopForUI::current()->Quit();
+  }
+
+  bool did_finish_loading() { return did_finish_loading_; }

[cbentzel, 2011/01/21 18:37:02]

Nit: const

[mmenke, 2011/01/21 20:12:20]

Done.

+
+ private:
+  bool did_finish_loading_;
+};
+
+// PrerenderManager that uses TestPrerenderContents.
+class WaitForLoadPrerenderContentsFactory : public PrerenderContents::Factory {
+ public:
+  virtual PrerenderContents* CreatePrerenderContents(
+      PrerenderManager* prerender_manager, Profile* profile, const GURL& url,
+        const std::vector<GURL>& alias_urls) {

[cbentzel, 2011/01/21 18:37:02]

Nit: line up with PrerenderManager.

[mmenke, 2011/01/21 20:12:20]

Done

+    return new TestPrerenderContents(prerender_manager, profile, url,
+                                     alias_urls);
+  }
+};
+
+}  // namespace
+
+class PrerenderBrowserTest : public InProcessBrowserTest {
+ public:
+  PrerenderBrowserTest() {
+    EnableDOMAutomation();
+  }
+
+  virtual void SetUpCommandLine(CommandLine* command_line) {
+    command_line->AppendSwitch(switches::kEnablePagePrerender);
+#if defined(OS_MACOSX)
+    // The plugins directory isn't read by default on the Mac, so it needs to be
+    // explicitly registered.
+    FilePath app_dir;
+    PathService::Get(chrome::DIR_APP, &app_dir);
+    command_line->AppendSwitchPath(
+        switches::kExtraPluginDir,
+        app_dir.Append(FILE_PATH_LITERAL("plugins")));
+#endif
+  }
+
+  void RunTestURL(const std::string& html_file) {
+    ASSERT_TRUE(test_server()->Start());
+
+    std::string src_path = "files/prerender/prerender_loader.html?";
+    src_path.append(html_file);
+    std::string dest_path = "files/prerender/";
+    dest_path.append(html_file);
+
+    GURL src_url = test_server()->GetURL(src_path);
+    GURL dest_url = test_server()->GetURL(dest_path);
+
+    Profile* profile = browser()->GetSelectedTabContents()->profile();
+    PrerenderManager* prerender_manager = profile->GetPrerenderManager();
+    ASSERT_TRUE(prerender_manager);
+
+    // This is needed to exit the event loop once the prerendered page has
+    // stopped loading.
+    prerender_manager->SetPrerenderContentsFactory(
+        new WaitForLoadPrerenderContentsFactory());
+
+    // ui_test_utils::NavigateToURL uses its own observer and message loop.
+    // Since the test needs to wait until the prerendered page has stopped
+    // loading, rathather than the page directly navigated to, need to
+    // handle browser navigation directly.
+    browser()->OpenURL(src_url, GURL(), CURRENT_TAB, PageTransition::TYPED);
+
+    ui_test_utils::RunMessageLoop();

[cbentzel, 2011/01/21 18:37:02]

So, if we break prerendering this will fail with a timeout since the UI message
loop quit never fires, right? 

[mmenke, 2011/01/21 20:12:20]

Yes.  I've thought about trying to get something to assert on instead in that
case, by using ui_test_utils::NavigateToURL(), which waits until the first
navigation is complete.  Then I could assert on the existence of the prerendered
page, and then run the message loop, but I'm concerned about race conditions
between the two pages.

While it could currently work fine, even if the prerendered page finishes first,
as NavigateToURL does the same thing we do, it still seems like a bad idea.


Another option would be to use the source page's onload event to create the
prefetch link, but I'm still worried about race conditions.  Depending on the
timing of things with such complicated relationships just doesn't seem like a
good idea.

+
+    TestPrerenderContents* prerender_contents =
+        static_cast<TestPrerenderContents*>(
+            prerender_manager->FindEntry(dest_url));
+
+    // Make sure the prefetech link was caught and the page was prerendered.
+    ASSERT_TRUE(prerender_contents != NULL);
+    ASSERT_TRUE(prerender_contents->did_finish_loading());
+
+    // Check if page behaves as expected while in prerendered state.
+    bool prerender_test_result;
+    ASSERT_TRUE(ui_test_utils::ExecuteJavaScriptAndExtractBool(
+        prerender_contents->render_view_host(), L"",
+        L"window.domAutomationController.send(DidPrerenderPass())",
+        &prerender_test_result));
+    EXPECT_TRUE(prerender_test_result);
+
+    ui_test_utils::NavigateToURL(browser(), dest_url);
+
+    // Make sure the PrerenderContents found earlier was used.
+    EXPECT_TRUE(prerender_manager->FindEntry(dest_url) == NULL);
+
+    // Check if page behaved as expected when actually displayed.
+    bool display_test_result;
+    ASSERT_TRUE(ui_test_utils::ExecuteJavaScriptAndExtractBool(
+        browser()->GetSelectedTabContents()->render_view_host(), L"",
+        L"window.domAutomationController.send(DidDisplayPass())",
+        &display_test_result));
+    EXPECT_TRUE(display_test_result);
+  }
+};
+
+// Checks that a page is correctly prerendered in the case of a
+// <link rel=prefetch> tag and then loaded into a tab in response to a
+// navigation.
+IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderPage) {
+  RunTestURL("prerender_page.html");
+}
+
+// Checks that plugins are not loaded while a page is being preloaded, but
+// are loaded when the page is displayed.
+IN_PROC_BROWSER_TEST_F(PrerenderBrowserTest, PrerenderDelayLoadPlugin) {
+  RunTestURL("plugin_delay_load.html");
+}