1 files changed, 54 insertions, 0 deletions
diff --git a/chromium/components/variations/caching_permuted_entropy_provider_unittest.cc b/chromium/components/variations/caching_permuted_entropy_provider_unittest.cc
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index 00000000000..c7139d8e1e2
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+++ b/chromium/components/variations/caching_permuted_entropy_provider_unittest.cc
@@ -0,0 +1,54 @@
+// Copyright 2014 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 "components/variations/caching_permuted_entropy_provider.h"
+
+#include <stddef.h>
+
+#include <string>
+
+#include "base/macros.h"
+#include "components/prefs/testing_pref_service.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace metrics {
+
+// Size of the low entropy source to use for the permuted entropy provider
+// in tests.
+const size_t kMaxLowEntropySize = 8000;
+
+// Field trial names used in unit tests.
+const char* const kTestTrialNames[] = {"TestTrial", "AnotherTestTrial",
+                                       "NewTabButton"};
+
+TEST(CachingPermutedEntropyProviderTest, HasConsistentResults) {
+  TestingPrefServiceSimple prefs;
+  CachingPermutedEntropyProvider::RegisterPrefs(prefs.registry());
+  const int kEntropyValue = 1234;
+
+  // Check that the caching provider returns the same results as the non caching
+  // one. Loop over the trial names twice, to test that caching returns the
+  // expected results.
+  PermutedEntropyProvider provider(kEntropyValue, kMaxLowEntropySize);
+  for (size_t i = 0; i < 2 * arraysize(kTestTrialNames); ++i) {
+    CachingPermutedEntropyProvider cached_provider(
+        &prefs, kEntropyValue, kMaxLowEntropySize);
+    const std::string trial_name =
+        kTestTrialNames[i % arraysize(kTestTrialNames)];
+    EXPECT_DOUBLE_EQ(provider.GetEntropyForTrial(trial_name, 0),
+                     cached_provider.GetEntropyForTrial(trial_name, 0));
+  }
+
+  // Now, do the same test re-using the same caching provider.
+  CachingPermutedEntropyProvider cached_provider(
+      &prefs, kEntropyValue, kMaxLowEntropySize);
+  for (size_t i = 0; i < 2 * arraysize(kTestTrialNames); ++i) {
+    const std::string trial_name =
+        kTestTrialNames[i % arraysize(kTestTrialNames)];
+    EXPECT_DOUBLE_EQ(provider.GetEntropyForTrial(trial_name, 0),
+                     cached_provider.GetEntropyForTrial(trial_name, 0));
+  }
+}
+
+}  // namespace metrics