Add support for the control group in the Simple Cache Experiment.

net/disk_cache/backend_unittest.cc

Index: net/disk_cache/backend_unittest.cc
diff --git a/net/disk_cache/backend_unittest.cc b/net/disk_cache/backend_unittest.cc
index 1dbdd56df102ef214386fe9a16c783434ceb9fa6..c3998e0461b8dfd7f51c329942346654dbc1e7bc 100644
--- a/net/disk_cache/backend_unittest.cc
+++ b/net/disk_cache/backend_unittest.cc
@@ -4,6 +4,7 @@
 
 #include "base/basictypes.h"
 #include "base/file_util.h"
+#include "base/metrics/field_trial.h"
 #include "base/port.h"
 #include "base/string_util.h"
 #include "base/stringprintf.h"
@@ -32,6 +33,8 @@
 
 using base::Time;
 
+namespace {
+
 // Tests that can run with different types of caches.
 class DiskCacheBackendTest : public DiskCacheTestWithCache {
  protected:
@@ -1677,6 +1680,72 @@ TEST_F(DiskCacheTest, WrongVersion) {
   delete cache;
 }
 
+class BadEntropyProvider : public base::FieldTrial::EntropyProvider {
+ public:
+  virtual ~BadEntropyProvider() {}
+
+  virtual double GetEntropyForTrial(const std::string& trial_name,
+                                    uint32 randomization_seed) const OVERRIDE {
+    return 0.5;
+  }
+};
+
+TEST_F(DiskCacheTest, SimpleCacheControlJoin) {
+  ASSERT_TRUE(CopyTestCache("insert_empty1"));
+
+  base::FieldTrialList field_trial_list(new BadEntropyProvider());
+  base::FieldTrialList::FactoryGetFieldTrial("SimpleCacheTrial", 100,
+                                             "Control", 2013, 12, 31, NULL);
+
+  base::Thread cache_thread("CacheThread");
+  ASSERT_TRUE(cache_thread.StartWithOptions(
+                  base::Thread::Options(MessageLoop::TYPE_IO, 0)));
+  net::TestCompletionCallback cb;
+
+  disk_cache::BackendImpl* cache = new disk_cache::BackendImpl(
+      cache_path_, cache_thread.message_loop_proxy(), NULL);
+  int rv = cache->Init(cb.callback());
+  ASSERT_EQ(net::ERR_FAILED, cb.GetResult(rv));
+
+  delete cache;
+}
+
+TEST_F(DiskCacheTest, SimpleCacheControlRestart) {
+  ASSERT_TRUE(CopyTestCache("simple_cache_control"));
+
+  base::FieldTrialList field_trial_list(new BadEntropyProvider());
+  base::FieldTrialList::FactoryGetFieldTrial("SimpleCacheTrial", 100,
+                                             "Control", 2013, 12, 31, NULL);
+
+  base::Thread cache_thread("CacheThread");
+  ASSERT_TRUE(cache_thread.StartWithOptions(
+                  base::Thread::Options(MessageLoop::TYPE_IO, 0)));
+  net::TestCompletionCallback cb;
+
+  disk_cache::BackendImpl* cache = new disk_cache::BackendImpl(
+      cache_path_, cache_thread.message_loop_proxy(), NULL);
+  int rv = cache->Init(cb.callback());
+  ASSERT_EQ(net::OK, cb.GetResult(rv));
+
+  delete cache;
+}
+
+TEST_F(DiskCacheTest, SimpleCacheControlLeave) {
+  ASSERT_TRUE(CopyTestCache("simple_cache_control"));

[pasko-google - do not use, 2013/04/19 18:00:30]

coud we create this file programmatically here? binary files are not easy to
read

[gavinp, 2013/04/20 07:17:32]

Mooted, as Ricardo has asked for the removal of these tests.

+
+  base::Thread cache_thread("CacheThread");
+  ASSERT_TRUE(cache_thread.StartWithOptions(
+                  base::Thread::Options(MessageLoop::TYPE_IO, 0)));
+  net::TestCompletionCallback cb;
+
+  disk_cache::BackendImpl* cache = new disk_cache::BackendImpl(
+      cache_path_, cache_thread.message_loop_proxy(), NULL);
+  int rv = cache->Init(cb.callback());
+  ASSERT_EQ(net::OK, cb.GetResult(rv));
+
+  delete cache;
+}
+

[rvargas (doing something else), 2013/04/19 17:40:55]

I would actually prefer not adding these tests. I believe they generate more
burden than the value they provide. Every line of code that we add has a cost
somewhere... building time, infrastructure costs (moving the tests to test bots,
waterfall and try bot cycle time), reviewing time, maintenance costs etc, and I
don't think this is worth it (even though you already paid the writing cost).

[gavinp, 2013/04/20 07:17:32]

Done.

 // Tests that the cache is properly restarted on recovery error.
 TEST_F(DiskCacheBackendTest, DeleteOld) {
   ASSERT_TRUE(CopyTestCache("wrong_version"));
@@ -2797,6 +2866,8 @@ TEST_F(DiskCacheBackendTest, ShaderCacheUpdateRankForExternalCacheHit) {
   entry->Close();
 }
 
+}  // namespace

[rvargas (doing something else), 2013/04/19 17:40:55]

I don't understand why you're placing half of the file on an anonymous
namespace.

[gavinp, 2013/04/20 07:17:32]

Moot, now that I"m not adding tests.

+
 void DiskCacheBackendTest::TracingBackendBasics() {
   InitCache();
   cache_ = new disk_cache::TracingCacheBackend(cache_);