[sensors] Add Generic Sensor platform unit tests.

device/generic_sensor/mock_platform_sensor_provider.h

+// Copyright 2016 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 DEVICE_GENERIC_SENSOR_MOCK_PLATFORM_SENSOR_PROVIDER_H_
+#define DEVICE_GENERIC_SENSOR_MOCK_PLATFORM_SENSOR_PROVIDER_H_
+
+#include "device/generic_sensor/platform_sensor_provider.h"
+
+namespace device {
+
+class MockPlatformSensorProvider : public PlatformSensorProvider {

[timvolodine, 2016/09/13 19:38:53]

I think we usually call these type of classes "fakes" instead of "mocks".

from the gmock documentation:
"
Note: It is easy to confuse the term fake objects with mock objects. Fakes and
mocks actually mean very different things in the Test-Driven Development (TDD)
community:

Fake objects have working implementations, but usually take some shortcut
(perhaps to make the operations less expensive), which makes them not suitable
for production. An in-memory file system would be an example of a fake.
Mocks are objects pre-programmed with expectations, which form a specification
of the calls they are expected to receive.
"

[timvolodine, 2016/09/13 19:38:53]

also small "fake" test classes can be placed inside the actual unittest if that
is more convenient (don't know if that's the case here)

[maksims (do not use this acc), 2016/09/16 09:22:19]

Good point, but these classes more or less resemble the real code. Thus, I think
we better stick with this kind of naming.

[timvolodine, 2016/09/19 17:14:29]

Why? Is there any reason it should be called a 'mock'? Looks like your classes
provide a very simple implementation which by definition is a 'fake' (as
described above).

[maksims (do not use this acc), 2016/09/21 11:05:19]

OK, I went through mock and fakes and it seems like we better use "fake_*" names
here.
Done!

+ public:
+  MockPlatformSensorProvider();
+  ~MockPlatformSensorProvider() override;
+
+  static MockPlatformSensorProvider* GetInstance();
+
+ protected:
+  scoped_refptr<PlatformSensor> CreateSensorInternal(
+      mojom::SensorType type,
+      mojo::ScopedSharedBufferMapping mapping,
+      uint64_t buffer_size) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(MockPlatformSensorProvider);
+};
+
+}  // namespace device
+
+#endif /* DEVICE_GENERIC_SENSOR_MOCK_PLATFORM_SENSOR_PROVIDER_H_ */

[timvolodine, 2016/09/13 19:38:53]

//

[maksims (do not use this acc), 2016/09/16 09:22:19]

Done.