fff_by_reference.cpp

/* Use of lambda functions for fff custom_fake
 *
 * this file contains an example of how to have "nested functions" 
 * within a test case for setting an fff custom_fake for pass by reference args
 *
 * This method for custom fakes allows all your test code to be self contained 
 * inside a test case instead of having global functions cluttering your test
 * code.
 * 
 * note that lambda captures are not supported
 */

#include "gtest/gtest.h"
#include "fff.h"
#include <functional>

DEFINE_FFF_GLOBALS;


/* The time structure */
typedef struct {
   int hour, min;
} Time;

/* Our fake function */
FAKE_VOID_FUNC(getTime, Time*);


template<typename L> auto to_function_pointer(L l)->decltype(&*l)
{
    return &*l;
}

/* A test using the getTime fake function */
TEST(FFFTestSuite, when_value_custom_fake_called_THEN_it_returns_custom_output)
{
    Time t;
    auto getTime_cf = [](Time *now) {
        now->hour = 2;
        now->min = 3;
    };

    getTime_fake.custom_fake = to_function_pointer(getTime_cf);

    getTime(&t);
    ASSERT_EQ(t.hour, 2);
    ASSERT_EQ(t.min,  3);
}

/* custiom fake with built in static sequence  */
TEST(FFFTestSuite, when_value_custom_fake_called_THEN_it_returns_custom_output_seq)
{
    Time t;
    auto getTime_cf = [](Time *now) {
        static size_t call_number = 0;
        static std::vector<Time> v = {
           {2,30},
           {4,30}
        };

        now->hour = v[call_number].hour;
        now->min = v[call_number].min;
        call_number++;
    };

    void( *fn)(Time*) = to_function_pointer(getTime_cf);
    getTime_fake.custom_fake = fn;

    getTime(&t);
    ASSERT_EQ(t.hour, 2);
    ASSERT_EQ(t.min,  30);

    getTime(&t);
    ASSERT_EQ(t.hour, 4);
    ASSERT_EQ(t.min,  30);
}