struct TypeIdProvider

This class is meant to provide a unique ID per type, which can be used at runtime to prevent

parameterized test cases to collide. Since the type is hidden under an interface, we need to

validate that we are not mixing fixtures, which will prevent wrong SetUp/TearDown from happening.

This works because the compiler will allocate a boolean for each type, and we can rely on its

address uniqueness for comparing whether two types are equal or not. Any other operation is not

permitted.