Add a switch for faking channels for Variations filtering.

chrome/browser/metrics/variations/variations_service.cc

 // Copyright (c) 2012 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 "chrome/browser/metrics/variations/variations_service.h"
 
 #include <set>
 
 #include "base/base64.h"
 #include "base/build_time.h"
@@ skipping 42 matching lines @@
     case Study_Channel_BETA:
       return chrome::VersionInfo::CHANNEL_BETA;
     case Study_Channel_STABLE:
       return chrome::VersionInfo::CHANNEL_STABLE;
   }
   // All enum values of |study_channel| were handled above.
   NOTREACHED();
   return chrome::VersionInfo::CHANNEL_UNKNOWN;
 }
 
+// Wrapper around channel checking, used to enable channel mocking for
+// testing. If the current browser channel is not UNKNOWN, this will return
+// that channel value. Otherwise, if the fake channel flag is provided, this
+// will return the fake channel. Failing that, this will return the UNKNOWN
+// channel.
+chrome::VersionInfo::Channel GetChannelForVariations() {
+  chrome::VersionInfo::Channel channel = chrome::VersionInfo::GetChannel();
+  if (channel != chrome::VersionInfo::CHANNEL_UNKNOWN)
+    return channel;
+  std::string forced_channel =
+      CommandLine::ForCurrentProcess()->GetSwitchValueASCII(
+          switches::kFakeVariationsChannel);
+  if (forced_channel == "stable")
+    channel = chrome::VersionInfo::CHANNEL_STABLE;
+  else if (forced_channel == "beta")
+    channel = chrome::VersionInfo::CHANNEL_BETA;
+  else if (forced_channel == "dev")
+    channel = chrome::VersionInfo::CHANNEL_DEV;
+  else if (forced_channel == "canary")
+    channel = chrome::VersionInfo::CHANNEL_CANARY;
+  else
+    DVLOG(1) << "Invalid channel provided: " << forced_channel;
+  return channel;
+}
+
 Study_Platform GetCurrentPlatform() {
 #if defined(OS_WIN)
   return Study_Platform_PLATFORM_WINDOWS;
 #elif defined(OS_MACOSX)
   return Study_Platform_PLATFORM_MAC;
 #elif defined(OS_CHROMEOS)
   return Study_Platform_PLATFORM_CHROMEOS;
 #elif defined(OS_ANDROID)
   return Study_Platform_PLATFORM_ANDROID;
 #elif defined(OS_IOS)
@@ skipping 202 matching lines @@
   variations_serial_number_ = seed.serial_number();
   return true;
 }
 
 // static
 bool VariationsService::ShouldAddStudy(
     const Study& study,
     const chrome::VersionInfo& version_info,
     const base::Time& reference_date) {
   if (study.has_filter()) {
-    if (!CheckStudyChannel(study.filter(), chrome::VersionInfo::GetChannel())) {

[Alexei Svitkine (slow), 2013/01/04 20:17:34]

VariationsService::CreateTrialsFromSeed() calls this for each study in the seed.
I suggest making the channel a param to ShouldAddStudy() to avoid doing the
command-line parsing for every study.

Alternatively, we could do the command-line parsing only once and store the
resulting chrome::VersionInfo::Channel as a field on the variations_service
(though, that will still need to be passed as a param, since this is a static
function).

+    if (!CheckStudyChannel(study.filter(), GetChannelForVariations())) {
       DVLOG(1) << "Filtered out study " << study.name() << " due to channel.";
       return false;
     }
 
     if (!CheckStudyLocale(study.filter(),
                           g_browser_process->GetApplicationLocale())) {
       DVLOG(1) << "Filtered out study " << study.name() << " due to locale.";
       return false;
     }
 
@@ skipping 215 matching lines @@
                                       variation_id);
     }
   }
 
   trial->SetForced();
   if (IsStudyExpired(study, reference_date))
     trial->Disable();
 }
 
 }  // namespace chrome_variations