CMock not able to mock stdio.h

[gpenghe]

Hi, I am trying to mock file operation functions like fopen etc. So I added the following line to my test file:

#include "mock_stdio.h"

However, calling fopen_IgnoreAndReturn failed as ceedling complains it is not defined.

So does CMock support mocking C library functions? If so how? Thanks.

[Xenoamor]

What does the contents of your mock_stdio.h file look like? Did CMock throw any errors or warnings when you ran it against stdio.h?

[ajones-pillar]

I'm trying to do the same thing. If I #include "mock_stdio.h", I receive a message "ERROR: Found no file 'stdio.h' in search paths". I've tried a number of configurations (including adding my target system's .h files to the source path, which avoided the error above, but had its own issues), but am thinking this might not be possible.

If this isn't possible, can we have that clarified and perhaps added to the documentation?

[gpenghe]

@Xenoamor Here is the content of mock_stdio.h:

/* AUTOGENERATED FILE. DO NOT EDIT. */
#ifndef _MOCK_STDIO_H
#define _MOCK_STDIO_H

#include "stdio.h"

/* Ignore the following warnings, since we are copying code */
#if defined(__GNUC__) && !defined(__ICC) && !defined(__TMS470__)
#if __GNUC__ > 4 || (__GNUC__ == 4 && (__GNUC_MINOR__ > 6 || (__GNUC_MINOR__ == 6 && __GNUC_PATCHLEVEL__ > 0)))
#pragma GCC diagnostic push
#endif
#if !defined(__clang__)
#pragma GCC diagnostic ignored "-Wpragmas"
#endif
#pragma GCC diagnostic ignored "-Wunknown-pragmas"
#pragma GCC diagnostic ignored "-Wduplicate-decl-specifier"
#endif

void mock_stdio_Init(void);
void mock_stdio_Destroy(void);
void mock_stdio_Verify(void);

#if defined(__GNUC__) && !defined(__ICC) && !defined(__TMS470__)
#if __GNUC__ > 4 || (__GNUC__ == 4 && (__GNUC_MINOR__ > 6 || (__GNUC_MINOR__ == 6 && __GNUC_PATCHLEVEL__ > 0)))
#pragma GCC diagnostic pop
#endif
#endif

#endif

[gpenghe]

@ajones-pillar I checked my project.yml. Under ":paths:->:include:", there is a line of - /usr/include. Hope it helps.

[Xenoamor]

Make your own stdio.h that has the function declarations that you are interested in Then run CMock against that

[tmilburn]

I'm also having issues mocking fopen.

When I create my own stdio.h with fopen in it I get the following error

ERROR: Test executable "test_paxlockDevices.out" failed. Produced no output to $stdout. And exited with status: [0] (count of failed tests). This is often a symptom of a bad memory access in source or test code.

I guess unity / cmock is using fopen internally.

[kristyan-osborne-paxton]

In case anyone is looking for an answer to this, what's been mentioned above is the correct way to do it.

Create your own header file with the definition for the library function. The thing that is probably catching a lot of people out is it's dependant on the c library you are using. If you are using GCC most function definitions will include one of the "THROW" macros. These are used for compatibility with c++. cmock is unable to create mocks if one of the throw macros is used. To solve this just redefine the one being used on your function.

#undef __THROW
#define __THROW

int clock_gettime (clockid_t __clock_id, struct timespec *__tp) __THROW;