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/* Copyright (c) 2013-2020, The Tor Project, Inc. */
/* See LICENSE for licensing information */
/**
* \file testsupport.h
*
* \brief Macros to implement mocking and selective exposure for the test code.
*
* Each Tor source file is built twice: once with TOR_UNIT_TESTS defined, and
* once with it undefined. The only difference between these configurations
* should be that when building for the tests, more functions are exposed as
* non-static, and a number of functions are declared as mockable.
**/
#ifndef TOR_TESTSUPPORT_H
#define TOR_TESTSUPPORT_H
/** The "STATIC" macro marks a function or variable that is static when
* building Tor for production, but non-static when building the unit
* tests.
*
* For example, a function declared as:
*
* STATIC int internal_function(void);
*
* should be only visible for the file on which it is declared, and in the
* unit tests.
*/
#ifdef TOR_UNIT_TESTS
#define STATIC
#else /* !defined(TOR_UNIT_TESTS) */
#define STATIC static
#endif /* defined(TOR_UNIT_TESTS) */
/** The "EXTERN" macro is used along with "STATIC" for variables declarations:
* it expands to an extern declaration when Tor building unit tests, and to
* nothing otherwise.
*
* For example, to declare a variable as visible only visible in one
* file and in the unit tests, you would put this in the header:
*
* EXTERN(int, local_variable)
*
* and this in the source:
*
* STATIC int local_variable;
*/
#ifdef TOR_UNIT_TESTS
#define EXTERN(type, name) extern type name;
#else
#define EXTERN(type, name)
#endif
/** Quick and dirty macros to implement test mocking.
*
* To use them, suppose that you have a function you'd like to mock
* with the signature "void writebuf(size_t n, char *buf)". You can then
* declare the function as:
*
* MOCK_DECL(void, writebuf, (size_t n, char *buf));
*
* and implement it as:
*
* MOCK_IMPL(void,
* writebuf,(size_t n, char *buf))
* {
* ...
* }
*
* For the non-testing build, this will expand simply into:
*
* void writebuf(size_t n, char *buf);
* void
* writebuf(size_t n, char *buf)
* {
* ...
* }
*
* But for the testing case, it will expand into:
*
* void writebuf__real(size_t n, char *buf);
* extern void (*writebuf)(size_t n, char *buf);
*
* void (*writebuf)(size_t n, char *buf) = writebuf__real;
* void
* writebuf__real(size_t n, char *buf)
* {
* ...
* }
*
* This is not a great mocking system! It is deliberately "the simplest
* thing that could work", and pays for its simplicity in its lack of
* features, and in its uglification of the Tor code. Replacing it with
* something clever would be a fine thing.
*
* @{ */
#ifdef TOR_UNIT_TESTS
/** Declare a mocked function. For use in headers. */
#define MOCK_DECL(rv, funcname, arglist) \
rv funcname ##__real arglist; \
extern rv(*funcname) arglist
/** Define the implementation of a mocked function. */
#define MOCK_IMPL(rv, funcname, arglist) \
rv(*funcname) arglist = funcname ##__real; \
rv funcname ##__real arglist
/** As MOCK_DECL(), but allow attributes. */
#define MOCK_DECL_ATTR(rv, funcname, arglist, attr) \
rv funcname ##__real arglist attr; \
extern rv(*funcname) arglist
/**
* Replace <b>func</b> (a mockable function) with a replacement function.
*
* Only usable when Tor has been built for unit tests. */
#define MOCK(func, replacement) \
do { \
(func) = (replacement); \
} while (0)
/** Replace <b>func</b> (a mockable function) with its original value.
*
* Only usable when Tor has been built for unit tests. */
#define UNMOCK(func) \
do { \
func = func ##__real; \
} while (0)
#else /* !defined(TOR_UNIT_TESTS) */
/** Declare a mocked function. For use in headers. */
#define MOCK_DECL(rv, funcname, arglist) \
rv funcname arglist
/** As MOCK_DECL(), but allow */
#define MOCK_DECL_ATTR(rv, funcname, arglist, attr) \
rv funcname arglist attr
/** Define the implementation of a mocked function. */
#define MOCK_IMPL(rv, funcname, arglist) \
rv funcname arglist
#endif /* defined(TOR_UNIT_TESTS) */
/** @} */
#endif /* !defined(TOR_TESTSUPPORT_H) */
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