Introduce NavigationSimulator to use in unit tests

content/public/test/navigation_simulator.h

+// Copyright 2017 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.
+
+#ifndef CONTENT_PUBLIC_TEST_NAVIGATION_SIMULATOR_H_
+#define CONTENT_PUBLIC_TEST_NAVIGATION_SIMULATOR_H_
+
+#include <memory>
+
+#include "ui/base/page_transition_types.h"
+
+class GURL;
+
+namespace content {
+
+class RenderFrameHost;
+struct Referrer;
+
+// An interface for simulating a navigation. Currently this only supports
+// renderer-initiated navigations.

[ncarter (slow), 2017/02/16 23:36:31]

Should this comment, or the comment before CreateRendererInitiated, make it
clear that this is for unittests, and should not be used for browsertests (since
it assumes |render_frame_host| is a TestRenderFrameHost)?

[clamy, 2017/02/17 17:34:52]

Done.

+// TODO(clamy): support browser-initiated navigations.
+class NavigationSimulator {
+ public:
+  // Creates a NavigationSimulator that will be used to simulate a
+  // renderer-initiated navigation to |original_url| received by

[nasko, 2017/02/16 18:47:59]

It isn't immediately clear to me what "received by" means? Is this the RFH that
the navigation will end up committing? If so, how would the test code know what
that would be?

[clamy, 2017/02/17 17:34:52]

It's a renderer-initiated navigation, so it's the RFH that corresponds the
RenderFrame that started it. I changed received to started, let me know if it is
clearer.

+  // |render_frame_host|.
+  static std::unique_ptr<NavigationSimulator> CreateRendererInitiated(

[ncarter (slow), 2017/02/16 23:36:31]

If we want a shorter name for this, it could be FromDocument() -- and the
future, browser-initiated variant being called FromBrowser.

[clamy, 2017/02/17 17:34:52]

I'm not sure it's clearer in that case, but I've used it in the new static
functions, whose names were a bit long otherwise.

+      const GURL& original_url,
+      RenderFrameHost* render_frame_host);
+

[nasko, 2017/02/16 18:47:59]

Side node: It will be great to later on have static methods that implement the
common patterns, such as "navigate and commit", so we can avoid boilerplate code
of creating this object, starting, committing.

[ncarter (slow), 2017/02/16 23:36:31]

An alternative to consider would be to support chaining -- the methods would
"return this", so you could do one liners like:

NavigationSimulator::CreateRendererInitiated(url,
rfh)->Start()->Redirect(url2)->Commit();

You could also add an implicit Start() and/or Commit() in the dtor, if it hadn't
been started.

[clamy, 2017/02/17 17:34:52]

I have updated the CL so that methods call any earlier omitted methods. I think
this should make it easier. I have added a static method for navigate and commit
or navigate and fail as well.

+  virtual ~NavigationSimulator();
+
+  // --------------------------------------------------------------------------
+
+  // The following functions should be used to simulate events happening during
+  // a navigation.
+  //
+  // Example of usage for a successful renderer-initiated navigation:
+  //   unique_ptr<NavigationSimulator> simulator =
+  //       NavigationSimulator::CreateRendererInitiated(
+  //           original_url, render_frame_host);
+  //   simulator.Start();

[ncarter (slow), 2017/02/16 23:36:32]

These would be ->'s, not .'s, right?

[clamy, 2017/02/17 17:34:52]

Done.

+  //   for (GURL redirect_url : redirects)
+  //     simulator.Redirect(redirect_url);
+  //   simulator.Commit();
+  //
+  // Example of usage for a failed renderer-initiated navigation:
+  //   unique_ptr<NavigationSimulator> simulator =
+  //       NavigationSimulator::CreateRendererInitiated(
+  //           original_url, render_frame_host);
+  //   simulator.Start();
+  //   for (GURL redirect_url : redirects)
+  //     simulator.Redirect(redirect_url);
+  //   simulator.Fail(net_error);

[ncarter (slow), 2017/02/16 23:36:31]

It's not clear what the identifier |net_error| indicates in this example code.
Can you replace it with a constant or a literal?

[clamy, 2017/02/17 17:34:52]

Done.

+  //   simulator.CommitErrorPage();
+  //
+  // Example of usage for a same-page renderer-initiated navigation:
+  //   unique_ptr<NavigationSimulator> simulator =
+  //       NavigationSimulator::CreateRendererInitiated(
+  //           original_url, render_frame_host);
+  //   simulator.CommitSamePage();
+
+  // Simulates the start of the navigation.
+  virtual void Start() {}

[ncarter (slow), 2017/02/16 23:36:32]

I'm curious what makes requiring Start() to be an explicit step? In what case
would you want to create a NavigationSimulator and not immediately Start it?

[clamy, 2017/02/17 17:34:52]

The goal is for people to create the NavigationSimulator, set up some parameters
(referrer, transition, etc...) and then start it once all parameters are
correct. I could have done that in the constructor, but I wanted to avoid having
many arguments in the constructor that would be useless for most users.

+
+  // Simulates a redirect to |new_url| for the navigation.
+  virtual void Redirect(const GURL& new_url) {}
+
+  // Simulates the commit of the navigation in the RenderFrameHost.
+  virtual void Commit() {}
+
+  // Simulates the navigation failing with the error code |error_code|.
+  virtual void Fail(int error_code) {}
+
+  // Simulates the commit of an error page following a navigation failure.
+  virtual void CommitErrorPage() {}
+
+  // Simulates the commit of a same-page navigation.

[nasko, 2017/02/16 18:47:59]

It will be nice to list what navigations are same-page and what it means/how it
differs.

[clamy, 2017/02/17 17:34:52]

Done.

+  virtual void CommitSamePage() {}
+
+  // --------------------------------------------------------------------------
+
+  // The following functions are used to specify the parameters of the
+  // navigation. Changes should be  made before calling |Start|, unless they are
+  // meant to apply to a redirect. In that case, they should be made before
+  // calling |Redirect|.
+
+  // The following parameters are constant during the navigation and may only be
+  // specified before calling |Start|.
+  virtual void SetTransition(ui::PageTransition transition) {}
+
+  // The following parameters can change during redirects. They should be
+  // specified before calling |Start| if they need to apply to the navigation to
+  // the original url. Otherwise, they should be specified before calling
+  // |Redirect|.
+  virtual void SetReferrer(const Referrer& referrer) {}
+};
+
+}  // namespace content
+
+#endif  // CONTENT_PUBLIC_TEST_NAVIGATION_SIMULATOR_H_