**STILLBAKING** Decouple disk cache tests from backends.

net/disk_cache/memory/memory_unittest.cc

+// Copyright (c) 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 <string>
+
+#include "net/base/io_buffer.h"
+#include "net/base/net_errors.h"
+#include "net/disk_cache/disk_cache.h"
+#include "net/disk_cache/disk_cache_test_util.h"
+#include "net/disk_cache/backend_tests.h"
+#include "net/disk_cache/entry_sync_tests.h"
+#include "net/disk_cache/entry_tests.h"
+#include "net/disk_cache/memory/mem_entry_impl.h"
+#include "net/disk_cache/memory/mem_backend_impl.h"
+
+namespace disk_cache {
+
+namespace {
+
+class MemoryCacheBackendTraits : public BackendTestTraits {
+ public:
+  MemoryCacheBackendTraits() {}
+
+  virtual ~MemoryCacheBackendTraits() {}
+
+  virtual Backend* CreateBackend(
+      const CreateBackendExtraData* extra_data,
+      const base::FilePath& cache_path,
+      int max_size,
+      base::MessageLoopProxy* task_runner) const OVERRIDE {
+    scoped_ptr<MemBackendImpl> mem_backend(new MemBackendImpl(NULL));
+    if (max_size)
+      mem_backend->SetMaxSize(max_size);
+    if (!mem_backend->Init())
+      return NULL;
+    return mem_backend.release();
+  }
+
+  virtual bool EnumerationsAreLexicographicByKey() const OVERRIDE {
+    return true;
+  }
+
+  virtual bool UsesCacheThread() const OVERRIDE { return false; }
+
+  virtual bool SetMaxSize(Backend* backend, int size) const OVERRIDE {
+    return static_cast<MemBackendImpl*>(backend)->SetMaxSize(size);
+  }
+
+  static const BackendTestTraits* Get() {
+    static MemoryCacheBackendTraits traits;
+    return &traits;
+  }
+};
+
+INSTANTIATE_TEST_CASE_P(MemoryOnlyCache, DiskCacheEntryTest,
+                        ::testing::Values(MemoryCacheBackendTraits::Get()));
+
+INSTANTIATE_TEST_CASE_P(MemoryOnlyCache, DiskCacheEntrySyncTest,
+                        ::testing::Values(MemoryCacheBackendTraits::Get()));
+
+INSTANTIATE_TEST_CASE_P(MemoryOnlyCache, DiskCacheBackendTest,
+                        ::testing::Values(MemoryCacheBackendTraits::Get()));
+
+class DiskCacheMemoryBackendTest : public DiskCacheBackendTest {};
+
+INSTANTIATE_TEST_CASE_P(MemoryOnlyCache, DiskCacheMemoryBackendTest,
+                        ::testing::Values(MemoryCacheBackendTraits::Get()));
+
+TEST_P(DiskCacheMemoryBackendTest, CreateBackend) {
+    // Test the private factory method(s).
+    scoped_ptr<disk_cache::Backend> cache;
+    cache = disk_cache::MemBackendImpl::CreateBackend(0, NULL);
+    ASSERT_TRUE(cache.get());
+    cache.reset();
+}
+
+}  // namespace
+
+}  // namespace disk_cache