This topic explains how to use declare test macro.
To illustrate the use of the __DECLARE_TEST macro, we can define the class TEgInvariant. It has a very simple state, a single data member iData. An object is in an invalid state when iData is greater than 100.
class TEgInvariant { public: void SetData(TUint a); TUint Data(); void DoSomeThing(); private: TUint iData; __DECLARE_TEST; };
Then we define the getter/setter functions for iData:
void TEgInvariant::SetData(TUint a) { iData=a; } TUint TEgInvariant::Data() { return iData; }
TEgInvariant::DoSomeThing() is a function that would perform some useful work. We verify the object’s state at its beginning and end through __TEST_INVARIANT.
void TEgInvariant::DoSomeThing() { __TEST_INVARIANT; //...do something with iData __TEST_INVARIANT; }
TEgInvariant::__DbgTestInvariant() performs the invariance test:
void TEgInvariant::__DbgTestInvariant() const { #if defined(_DEBUG) if(iData > 100) User::Invariant(); #endif }
We could test the class with the following code:
TEgInvariant Eg; Eg.SetData(10); Eg.DoSomeThing(); Eg.SetData(1000); Eg.DoSomeThing();
In debug builds, the second call to DoSomeThing() causes a panic, alerting us to a problem in the code that needs fixing.