diff options
| -rw-r--r-- | changes/fancy_testing | 12 | ||||
| -rw-r--r-- | src/common/testsupport.h | 66 |
2 files changed, 78 insertions, 0 deletions
diff --git a/changes/fancy_testing b/changes/fancy_testing index ad197c6f5..89876ff27 100644 --- a/changes/fancy_testing +++ b/changes/fancy_testing @@ -14,3 +14,15 @@ tests (and a new src/or/tor-cov target) to build with gcov test coverage support. + o Testing: + + - We now have rudimentary function mocking support that our unit + tests can use to test functions in isolation. Function mocking + lets the tests temporarily replace a function's dependencies with + stub functions, so that the tests can check the function without + invoking the other functions it calls. + + + + + diff --git a/src/common/testsupport.h b/src/common/testsupport.h index c6777d0cb..4a4f50b69 100644 --- a/src/common/testsupport.h +++ b/src/common/testsupport.h @@ -10,5 +10,71 @@ #define STATIC static #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 +#define MOCK_DECL(rv, funcname, arglist) \ + rv funcname ##__real arglist; \ + extern rv(*funcname) arglist +#define MOCK_IMPL(rv, funcname, arglist) \ + rv(*funcname) arglist = funcname ##__real; \ + rv funcname ##__real arglist +#define MOCK(func, replacement) \ + do { \ + (func) = (replacement); \ + } while (0) +#define UNMOCK(func) \ + do { \ + func = func ##__real; \ + } while (0) +#else +#define MOCK_DECL(rv, funcname, arglist) \ + rv funcname arglist +#define MOCK_IMPL(rv, funcname, arglist) \ + rv funcname arglist +#endif +/** @} */ + #endif |