'(maybe you meant to use ‘->’ ?)' in gmock test - c++

Question

I have a unit test using gtest and gmock.
These are provided, and in my turn I should make them pass.
I have a RentalAdministration Object, which takes (in some methods) a Car object pointer. One of the functions looks like this:
bool RentalAdministration::Add(Car *car){
if(!car){
throw invalid_argument("Car parameter can't be null!");
}
if(FindCar(car->GetLicencePlate()) != NULL){
return false;
}
cars.push_back(car);
return true;
}
One of such tests looks like his:
TEST(RentalAdministrationAdd, test_add_car_to_empty_administration)
{
RentalAdministration admin;
Car *car;
EXPECT_CALL(car, GetLicencePlate()).WillOnce(Return("fh-01-ict"));
EXPECT_TRUE(admin.Add(&car));
}
When I try to make these tests, I get loads of errors, all of which are alike:
g++ -Wall -Werror -pedantic -ggdb -O0 -std=c++98 -Iproduct -Itest test/RentalAdministrationTest.cpp product/RentalAdministration.cpp -lgtest -lgmock -lgmock_main -lpthread -o RentalAdministrationTest
In file included from /usr/include/gmock/gmock-generated-function-mockers.h:43:0,
                 from /usr/include/gmock/gmock.h:61,
                 from test/RentalAdministrationTest.cpp:2:
test/RentalAdministrationTest.cpp: In member function ‘virtual void RentalAdministrationAdd_test_add_car_to_empty_administration_Test::TestBody()’:
test/RentalAdministrationTest.cpp:13:5: error: request for member ‘gmock_GetLicencePlate’ in ‘car’, which is of pointer type ‘Car*’ (maybe you meant to use ‘->’ ?)
     EXPECT_CALL(car, GetLicencePlate()).WillOnce(Return("fh-01-ict"));
     ^
In file included from /usr/include/gtest/gtest.h:58:0,
                 from /usr/include/gmock/internal/gmock-internal-utils.h:47,
                 from /usr/include/gmock/gmock-actions.h:46,
                 from /usr/include/gmock/gmock.h:58,
                 from test/RentalAdministrationTest.cpp:2:
test/RentalAdministrationTest.cpp:14:31: error: no matching function for call to ‘RentalAdministration::Add(Car**)’
     EXPECT_TRUE(admin.Add(&car));
                               ^
I wonder what I am doing wrong here. I'm just starting off with C++.
btw: I am compiling in g++ and have version 98.
Thanks.
Edit: excuse me for not posting this, but I have a mock file for Car.h which is in the same folder as the test itself.
#ifndef __CAR_H
#define __CAR_H
#include "gmock/gmock.h"
#include <string>
using namespace std;
class Car
{
public:
MOCK_CONST_METHOD0(GetLicencePlate, string());
MOCK_METHOD0(Rent, bool());
MOCK_METHOD1(Return, double(int kilometers));
MOCK_METHOD0(Clean, void());
};
#endif
Edit1: As suggested I have tried to use the reference (&) of Car*.
This kills the error I've stated above, but leaves me with some other errors:
error: cannot declare field ‘AdminTest::car’ to be of abstract type ‘Car’
Car car;
error: ‘class Car’ has no member named ‘gmock_GetLicencePlate’

Answer 1

car is a pointer to Car. Its type is: Car*. In order to call Car members from a Car*, you must dereference the pointer. This is automatically done when using the car->x syntax, which is equivalent to (*car).x.
I assume that EXPECT_CALL requires a non-pointer argument. Therefore, you can get a reference to car and pass it to the macro:
Car& car_ref = *car;
EXPECT_CALL(car_ref, GetLicencePlate()).WillOnce(Return("fh-01-ict"));

Answer 2

First is the pointer issue, that Vittorio already said but, also, you need to mock Car object to use EXCEPT_CALL:
class MockCar : public Car{
// Here I assume that original method is const
MOCK_CONST_METHOD0(GetLicencePlate);
}
TEST(RentalAdministrationAdd, test_add_car_to_empty_administration)
{
RentalAdministration admin;
MockCar car;
EXPECT_CALL(car, GetLicencePlate()).WillOnce(Return("fh-01-ict"));
EXPECT_TRUE(admin.Add(&car));
}
You can see in my examle that you are not using real car object but a Mock one where you can control access and force return values

Answer 3

I have found the solution.
For anyone wondering: Inside one class (RentalAdministration) I had included the Car.h file from the cars folder. (like #include "cars/Car.h")
However, for the test a different Car.h should be used. Therefore, changing to #include "Car.h" made it work.