Modern C++ Programming with Test-Driven Development

5.4 A Hand-Crafted Test Double

To use a test double, you must be able to supplant the behavior of the CurlHttp class. C++ provides many different ways, but the predominant manner is to take advantage of polymorphism. Let’s take a look at the Http interface that the CurlHttp class implements (realizes):

virtual ~Http() {}
virtual void initialize() = 0;
virtual std::string get(const std::string& url) const = 0;

Your solution is to override the virtual methods on a derived class, provide special behavior to support testing in the override, and pass the Place Description Service code a base class pointer.

Let’s see some code.

TEST_F(APlaceDescriptionService, ReturnsDescriptionForValidLocation) ...