Allow browser tests to run with dynamic CLD data.

chrome/browser/translate/translate_browser_test_utils.h

+// 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.
+
+#ifndef CHROME_BROWSER_TRANSLATE_TRANSLATE_BROWSER_TEST_UTILS_H_
+#define CHROME_BROWSER_TRANSLATE_TRANSLATE_BROWSER_TEST_UTILS_H_
+
+#include "base/macros.h"
+
+namespace test {
+
+// A utility class that sets up CLD dynamic data upon calling Init() and cleans
+// it up when destroyed.
+//
+// This class is intended to be instantiated within IN_PROC_BROWSER_TEST_F

[msw, 2014/05/19 18:54:48]

Can InProcessBrowserTest subclasses own the ScopedCLDDynamicDataHarness object,
and call init in a SetUp() override, so each of its tests don't have to run all
this file copying and cleanup separately (and apparently redundantly)? If so,
it'd be worth recommending that pattern here, and updating your followup CLs,
like https://codereview.chromium.org/292723003/, to do that instead.

[Andrew Hayden (chromium.org), 2014/05/19 20:54:02]

That's certainly a valid pattern. I'll add a note to this effect to the comment.
Good point.

I'll look at the followup CLs. I think one of them would benefit from that
pattern, the others (like browser_browsertest) not so much. Thanks!

+// test fixtures; it uses ASSERT macros for correctness, so that tests will
+// fail gracefully in error conditions. Sample use:
+//
+//   #include "chrome/browser/translate/translate_browser_test_utils.h"
+//
+//   IN_PROC_BROWSER_TEST_F(BrowserTest, PageLanguageDetection) {
+//     test::ScopedCLDDynamicDataHarness dynamic_data_scope;
+//     ASSERT_NO_FATAL_FAILURE(dynamic_data_scope.Init());
+//     // ... your code that depends on language detection goes here
+//   }
+//
+// NB: Test data lives under src/chrome/test/data/cld2_component
+class ScopedCLDDynamicDataHarness {
+ public:
+  // Constructs the object, but does nothing. Call Init() to prepare the
+  // harness, and enclose that call in ASSERT_NO_FATAL_FAILURE(...).
+  ScopedCLDDynamicDataHarness();
+
+  // Reverses the work done by the constructor: any files and/or directories
+  // that would be created by the constructor are immediately and irrevocably
+  // deleted.
+  // If dynamic data is not currently available for any reason, this method has
+  // no net effect on the runtime.
+  ~ScopedCLDDynamicDataHarness();
+
+  // Call this method, wrapping it in ASSERT_NO_FATAL_FAILURE, to initialize
+  // the harness and trigger test failure of initialization fails.
+  void Init() OVERRIDE;
+
+ private:
+  void ClearStandaloneDataFileState();
+
+  DISALLOW_COPY_AND_ASSIGN(ScopedCLDDynamicDataHarness);
+};
+
+}  // namespace test
+
+#endif  // CHROME_BROWSER_TRANSLATE_TRANSLATE_BROWSER_TEST_UTILS_H_