Mocking c library

Eventhough standard C library functions can be mocked, it is worth to notice that some of these may in fact be macros disguised as functions. This depends on the library installed, but some versions of stdlib may have this issue for feof, setjmp and longjmp.

The exit function is generally not mockable - typically the compiler will assume that exit never returns to the caller. Therefore it will not generate normal stack cleanup code and the mock functionality will not work correctly.

sample12 below,2.1is an example on a test that mocks printf in order to make a general validation of the format string.

  void mock_printf(char *fmt, ...) {
    VALIDATE(fmt==0, FALSE);

  void test_printf(void) {
    EXPECT(invalid, TRUE);
    ALLOW_MOCK( printf, mock_printf);



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