I found the fix. Hope this helps for anyone else struggling with these type of things…
Instead of (GameCharacter.h – line 27):
ICombatAction* combatAction;
It should be (GameCharacter.h – line 27):
class ICombatAction *combatAction;
Aswell, I had to include “TestCombatAction.h” in “GameCharacter.cpp”
// GameCharacter.cpp
#include "TestCombatAction.h"