The first argument to ASSERT_PRED1(pred1, val1);
should be a callable object; a unary-function or functor.
For example, if you can use C++11 lambdas, you could do:
ASSERT_PRED1([&testEntity](int i) { return testEntity.function_to_test(i); }, b);
Or if you want to use a unary function helper:
struct TesterA : public std::unary_function <int, bool> {
explicit TesterA(A& a) : a_(a) {}
bool operator()(int i) { return a_.function_to_test(i); }
A& a_;
};
ASSERT_PRED1(TesterA(testEntity), b);