Using a mock LevelDBTransaction for corruption tests.

content/browser/indexed_db/indexed_db_browsertest_mock_factory.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 CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_BROWSERTEST_MOCK_FACTORY_H_
+#define CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_BROWSERTEST_MOCK_FACTORY_H_
+
+#include <map>
+
+#include "content/browser/indexed_db/indexed_db_class_factory.h"
+
+namespace content {
+
+class LevelDBTransaction;
+class LevelDBDatabase;
+
+enum FailClass {
+  FAIL_CLASS_NOTHING,
+  FAIL_CLASS_LEVELDB_TRANSACTION,
+};
+
+enum FailMethod {
+  FAIL_METHOD_NOTHING,
+  FAIL_METHOD_COMMIT,
+  FAIL_METHOD_GET,
+};
+
+class IndexedDBBrowserTestClassFactory : public IndexedDBClassFactory {

[jsbell, 2014/06/19 21:08:47]

Looking around the Chromium code, it's more common to name these MockXXX e.g.
MockIndexedDBClassFactory, with the file named mock_xxx.h

Does this need the BrowserTest qualifier?

[cmumford, 2014/06/19 22:17:11]

I'll rename to MockXXX.

Here's where I was going with the names: I've been thinking that Mock<ClassName>
named classes would be "pure mock" objects (See
https://codereview.chromium.org/308103004/diff/60001/content/browser/indexed_...
for example). Most tests just need a phony mock object so that they can
instantiate the actual class they want to test. This is the most reusable type
of mock object.

A test that wants more specific behavior would create their own mock
implementation (ideally in that tests's *.cc file) - and then it would be named
something like Mock<TestName><ClassName>.

I can also see mock objects that serve a specific purpose, but can be shared
between tests - and I think this might be a candidate. Then it would be named
Mock<WhatItDoes><ClassName>. I can't think of a good "WhatItDoes" name for this
- "MockFailingIndexedDBClassFactory" just doesn't sound right.

So I don't yet have any other tests that I can see using what is currently named
IndexedDBBrowserTestClassFactory. What do you think about naming it
MockBrowserTestIndexedDBClassFactory, and then renaming it to something else
if/when it needs to be reused? 

I'm not married to any of this so let me know what you prefer.

[jsbell, 2014/06/19 22:36:03]

I'm good with MockBrowserTestIndexedDBClassFactory for now.

+ public:
+  IndexedDBBrowserTestClassFactory();
+  virtual ~IndexedDBBrowserTestClassFactory();
+  virtual LevelDBTransaction* CreateLevelDBTransaction(
+      LevelDBDatabase* db) OVERRIDE;
+
+  void FailOperation(FailClass failure_class,
+                     FailMethod failure_method,
+                     int fail_on_instance_num,
+                     int fail_on_call_num);
+  void Reset();
+
+ private:
+  FailClass failure_class_;
+  FailMethod failure_method_;
+  std::map<FailClass, int> instance_count_;
+  std::map<FailClass, int> fail_on_instance_num_;
+  std::map<FailClass, int> fail_on_call_num_;
+  bool only_trace_calls_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_INDEXED_DB_INDEXED_DB_BROWSERTEST_MOCK_FACTORY_H_