Modularize Compact Language Detector 2 (CLD2) data sources

chrome/browser/translate/cld_data_harness.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_CLD_DATA_HARNESS_H_
+#define CHROME_BROWSER_TRANSLATE_CLD_DATA_HARNESS_H_
+
+#include "base/files/file_path.h"
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+
+namespace test {
+
+// A utility class that sets up CLD dynamic data upon calling Init() and cleans
+// it up when destroyed.
+// Test data lives under: src/chrome/test/data/cld2_component
+//
+// This class is intended to be instantiated within IN_PROC_BROWSER_TEST_F
+// test fixtures; it uses ASSERT macros for correctness, so that tests will
+// fail gracefully in error conditions. Sample use:
+//
+//   IN_PROC_BROWSER_TEST_F(BrowserTest, PageLanguageDetection) {
+//     scoped_ptr<test::CldDataHarness> cld_data_scope =
+//       test::CreateCldDataHarness();
+//     ASSERT_NO_FATAL_FAILURE(cld_data_scope->Init());
+//     // ... your code that depends on language detection goes here
+//   }
+//
+// If you have a lot of tests that need language translation features, you can
+// add an instance of the CldDataHarness to your test class' private
+// member variables and add the call to Init() into SetUpOnMainThread.
+// Sample use:
+//
+//   class MyTestClass : public InProcessBrowserTest {
+//    public:
+//     MyTestClass() :
+//       cld_data_scope(test::CreateCldDataHarness()) {
+//     }
+//     virtual void SetUpOnMainThread() OVERRIDE {
+//       cld_data_scope->Init();
+//       InProcessBrowserTest::SetUpOnMainThread();
+//     }
+//    private:
+//     scoped_ptr<test::CldDataHarness> cld_data_scope;
+//   };
+//
+class CldDataHarness {
+ public:
+  // Reverses the work done by the Init() method: any files and/or directories
+  // that would be created by Init() (whether it was called or not) are
+  // immediately deleted.
+  // If dynamic data is not currently available for any reason, this method has
+  // no effect.
+  virtual ~CldDataHarness() {}
+
+  // Call this method, wrapping it in ASSERT_NO_FATAL_FAILURE, to initialize
+  // the harness and trigger test failure if initialization fails.
+  virtual void Init() = 0;
+
+ protected:
+  // Returns the version number of the Component Updater "extension" in the
+  // test directory. This generally corresponds the the revision of CLD2 that
+  // the data was built from. The version number is also part of the path that
+  // would be present at runtime if the component installer was used as the
+  // CLD2 data source.
+  const base::FilePath::CharType* GetTestDataSourceCrxVersion();
+
+  // Returns the path to the Component Updater "extension" files in the test
+  // directory. Within, there is a real copy of the CLD2 dynamic data that can
+  // be used in testing scenarios without accessing the network.
+  void GetTestDataSourceDirectory(base::FilePath* out_path);
+};
+
+// Static factory function that returns a data harness defined by the
+// implementation, which must be a subclass of CldDataHarness.
+scoped_ptr<CldDataHarness> CreateCldDataHarness();
+
+}  // namespace test
+
+#endif  // CHROME_BROWSER_TRANSLATE_CLD_DATA_HARNESS_H_