Writing custom Hamcrest matchers

The previous section ended with the Equals matcher specialized to call compareEq for floating-point types. We also modified the tests for large floating-point values because they could use the Hamcrest style and the Equals matcher.

We left the tests for small floating-point values unchanged because those tests need to make sure that the actual and expected values are not equal.

We want to update the small floating-point value tests and need a way to test for not equal values. Maybe we could create a new matcher called NotEquals, or we could put the not keyword in front of the Equals matcher.

I’d like to avoid the need for a new matcher if possible. We don’t really need any new behavior—we just need to flip the results of the existing Equals matcher. Let’s try modifying the small floating-point value tests to look like this in Hamcrest.cpp:

TEST("Test small float values")
{
    //...