metrics: add PersistentInteger unit test.

BUG=chromium:339588
TEST=P2_TEST_FILTER="metrics::*" FEATURES=test emerge-panther -v platform2
BRANCH=none

Change-Id: I78bdd8eed2da69ae6284d0f7770918d1be9f0e9f
Reviewed-on: https://chromium-review.googlesource.com/190121
Reviewed-by: Luigi Semenzato <semenzato@chromium.org>
Tested-by: Luigi Semenzato <semenzato@chromium.org>
Commit-Queue: Luigi Semenzato <semenzato@chromium.org>

metrics/metrics.gyp

@@ -62,6 +62,15 @@
     }],
     ['USE_test == 1', {
       'targets': [
+        {
+          'target_name': 'persistent_integer_test',
+          'type': 'executable',
+          'includes': ['../common-mk/common_test.gypi'],
+          'sources': [
+            'persistent_integer.cc',
+            'persistent_integer_test.cc',
+          ]
+        },
         {
           'target_name': 'metrics_library_test',
           'type': 'executable',

metrics/persistent_integer_test.cc

@@ -0,0 +1,67 @@
+// Copyright (c) 2014 The Chromium OS 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 <gtest/gtest.h>
+
+#include <base/compiler_specific.h>
+#include <base/file_util.h>
+#include <base/files/file_enumerator.h>
+
+#include "metrics/persistent_integer.h"
+
+const char kBackingFileName[] = "1.pibakf";
+const char kBackingFilePattern[] = "*.pibakf";
+
+using chromeos_metrics::PersistentInteger;
+
+class PersistentIntegerTest : public testing::Test {
+
+  virtual void SetUp() OVERRIDE {
+    // Set testing mode.
+    chromeos_metrics::PersistentInteger::SetTestingMode(true);
+  }
+
+  virtual void TearDown() OVERRIDE {
+    // Remove backing files.  The convention is that they all end in ".pibakf".
+    base::FileEnumerator f_enum(base::FilePath("."),
+                                false,
+                                base::FileEnumerator::FILES,
+                                FILE_PATH_LITERAL(kBackingFilePattern));
+    for (base::FilePath name = f_enum.Next();
+         !name.empty();
+         name = f_enum.Next()) {
+      base::DeleteFile(name, false);
+    }
+  }
+};
+
+TEST_F(PersistentIntegerTest, BasicChecks) {
+  scoped_ptr<PersistentInteger> pi(new PersistentInteger(kBackingFileName));
+
+  // Test initialization.
+  EXPECT_EQ(0, pi->Get());
+  EXPECT_EQ(kBackingFileName, pi->Name());  // boring
+
+  // Test set and add.
+  pi->Set(2);
+  pi->Add(3);
+  EXPECT_EQ(5, pi->Get());
+
+  // Test persistence.
+  pi.reset(new PersistentInteger(kBackingFileName));
+  EXPECT_EQ(5, pi->Get());
+
+  // Test GetAndClear.
+  EXPECT_EQ(5, pi->GetAndClear());
+  EXPECT_EQ(pi->Get(), 0);
+
+  // Another persistence test.
+  pi.reset(new PersistentInteger(kBackingFileName));
+  EXPECT_EQ(0, pi->Get());
+}
+
+int main(int argc, char** argv) {
+  testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}