Specifying output string argument with GoogleMock

Question

I'm evaluating the Google Test/Mock as a framework for unit tests of my C code.

How can I specify the output string argument for the function I would like to mock?

Here I have int get_int_param(const char *) is the function to test and it uses int _get_text_file_content(const char *fn, char *content) function that I want to mock.

How to specify this char *content that is going to be the result of execution of mocking function?

I'm struggling with this code:

TEST(GetParameterTest,Positiv){
   const static int strLen=29;
   char *text=(char *)calloc(strLen,1);
   strcpy(text, "param1=1\nparam2=42\nparam3=3");

   MokedFunctions mokedFunctions;
   EXPECT_CALL(mokedFunctions, _get_text_file_content("process.conf",_)).Times(AtLeast(1)).WillOnce(SetArgReferee<1>(text));

   EXPECT_EQ(1, get_int_param("param1"));
}

and got this compile error:

/usr/include/gmock/gmock-more-actions.h: In instantiation of ‘typename 
testing::internal::Function<F>::Result testing::SetArgRefereeActionP<k, 
value_type>::gmock_Impl<F>::gmock_PerformImpl(const args_type&, 
arg0_type, arg1_type, arg2_type, arg3_type, arg4_type, arg5_type, 
arg6_type, arg7_type, arg8_type, arg9_type) const [with arg0_type = 
const char*; arg1_type = char*; arg2_type = 
testing::internal::ExcessiveArg; arg3_type = 
testing::internal::ExcessiveArg; arg4_type = 
testing::internal::ExcessiveArg; arg5_type = 
testing::internal::ExcessiveArg; arg6_type = 
testing::internal::ExcessiveArg; arg7_type = 
testing::internal::ExcessiveArg; arg8_type = 
testing::internal::ExcessiveArg; arg9_type = 
testing::internal::ExcessiveArg; F = int(const char*, char*); int k = 1; 
value_type = char*; typename testing::internal::Function<F>::Result = 
int; testing::SetArgRefereeActionP<k, 
value_type>::gmock_Impl<F>::args_type = std::tuple<const char*, char*>]’:

 /usr/include/gmock/gmock-generated-actions.h:664:23:   required from 
 ‘static Result testing::internal::ActionHelper<Result, 
 Impl>::Perform(Impl*, const std::tuple<_U1, _U2>&) [with A0 = const 
 char*; A1 = char*; Result = int; Impl = 
 testing::SetArgRefereeActionP<1, char*>::gmock_Impl<int(const char*, 
 char*)>]’

 /usr/include/gmock/gmock-more-actions.h:168:1:   required from 
 ‘testing::SetArgRefereeActionP<k, 
 value_type>::gmock_Impl<F>::return_type 
 testing::SetArgRefereeActionP<k, 
 value_type>::gmock_Impl<F>::Perform(const args_type&) [with F = 
 int(const char*, char*); int k = 1; value_type = char*; 
 testing::SetArgRefereeActionP<k, 
 value_type>::gmock_Impl<F>::return_type = int; 
 testing::SetArgRefereeActionP<k, value_type>::gmock_Impl<F>::args_type 
 = std::tuple<const char*, char*>]’

 test_param.cpp:68:1:   required from here
 /usr/include/gmock/gmock-more-actions.h:175:3: error: size of array is negative
 GTEST_COMPILE_ASSERT_(internal::is_reference<argk_type>::value,
 ^
 In file included from /usr/include/gmock/gmock.h:65:0,
             from test_param.cpp:2:
  /usr/include/gmock/gmock-more-actions.h:177:28: error: assignment of read-only location ‘std::get<1u, {const char*, char*}>((* & args))’
    ::std::tr1::get<k>(args) = value;
                        ^
  make[1]: *** [test_param.o] Error 1

What I'm doing wrong?

Ruddy

Answer 1

SetArgReferee expects the argument to be a C++ reference, which it's not it your case.

In general, in order to better understand these actions it helps to think of them as operations over the argument arg:

• SetArgPointee(value) is essentially *arg = value (arg must be a pointer)
• SetArgReferee(value) is arg = value (arg must be a reference)
• SetArrayArgument(first, last) is memcpy(arg, first, last - first) (arg must be a pointer)
• SaveArg(ptr) is *ptr = arg
• SaveArgPointee(ptr) is *ptr = *arg (arg must be a pointer)

Given that, it becomes obvious that the action you need is SetArrayArgument<1>(text, text + strlen(text) + 1).

Spohr

Answer 2

You are using a C++ testing framework for C code. Unless you're willing to compile your code with g++ (instead of gcc), it's not going to work. Gcc can't compile C++ code.

Telophase

Yes sure, I'm compiling my C code with gcc and then compile my tests and link them with g++. No problem, it is working quite good. – Ruddy

Ok, so are you doing something like this? #19553305 – Telophase

yep, my solution is a bit dirty but it is based on this post – Ruddy

In line EXPECT_CALL(mokedFunctions, _get_text_file_content("process.conf", _ )).Times(AtLeast(1)).WillOnce(SetArgReferee<1>(text)); you have an underscore as an argument. I'm not an expert at google mock so I could be missing something but that doesn't look right. – Telophase

::testing::_ is a wildcard from GMock. It means that there is any value of correct type is expected. My understanding of this is: "I'm expecting everything that is correct pointer as an input" and then I want to specify the output at this pointer, that in turn is predefined (SetArgReferee). – Ruddy

Hey, just a bit of a shot in the dark but it looks like SetArgReferee only accepts reference or value. I think you're supposed to use SetArgPointee for pointers. See here: #8846253 – Telophase

It looks now like it tries to dereference the pointer. gmock-actions.h:695:31: error: invalid conversion from ‘char*’ to ‘char’ [-fpermissive] – Ruddy

Try just using a string there and pass in a reference to SetArgReferee – Telophase