Hello my friends, I wonder how to mock a c library function by using cpputest. Thanks very much.

[FrankLiang826]

I want to mock a c library function, i.e. int abs(int a). I writen my testcase like this, but when I execute it, the testcase call the real one, not the mocked one. I want to know how to mock a c library function, especially the variadic function, i.e. open and ioctl.
source file:src.cpp
#include <stdlib.h> int abs_test() { return abs(-1); }
include file:src.h
int abs_test();
test file:test.cpp

#include "CppUTest/TestHarness.h"
#include "CppUTestExt/MockSupport_c.h"
#include "src.h"
TEST_GROUP(MockDocumentation_C)
{
    void teardown()
    {
        mock_c()->clear();
    }
};

int abs(int b)
{
    mock_c()->actualCall("abs")->withIntParameters("a", b);
    return mock_c()->returnValue().value.intValue;
}

TEST(MockDocumentation_C, abs_test) {
    mock_c()->expectOneCall("abs")->withIntParameters("a", -1)->andReturnIntValue(2);
    CHECK_EQUAL(abs_test(), 2);
    mock_c()->checkExpectations();
}

TEST(MockDocumentation_C, abs) {
    mock_c()->expectOneCall("abs")->withIntParameters("a", -1)->andReturnIntValue(2);
    CHECK_EQUAL(abs(-1), 2);
    mock_c()->checkExpectations();
}

The second one can pass, but the first one fail.
And I also want to know whether a parameter can be set to an arbitrary value rather than a fixed value when I mock a function?