Modern C++ Programming with Test-Driven Development

8.15 Spying to Sense Using a Mock

One of the goals of ​writeSnippet​ is to send the total seconds to the descriptor. In the prior section, we inspected this value by turning it into a member variable. We can instead have the WavReader use a test double of the descriptor that captures the total seconds sent to it.

You learned about how to create test doubles using Google Mock in Chapter 5, ​Test Doubles​. Since we’re using CppUTest for our current example, we’ll use its own mock tool, CppUMock. As with Google Mock, we define a derivative of WavDescriptor that will spy on messages sent to its ​add​ function.

class MockWavDescriptor : public WavDescriptor {
public:
   MockWavDescriptor(): WavDescriptor("") {}