src/common/testsupport.h

   1 /* Copyright (c) 2013-2017, The Tor Project, Inc. */
   2 /* See LICENSE for licensing information */
   3
   4 #ifndef TOR_TESTSUPPORT_H
   5 #define TOR_TESTSUPPORT_H
   6
   7 #ifdef TOR_UNIT_TESTS
   8 #define STATIC
   9 #define EXTERN(type, name) extern type name;
  10 #else
  11 #define STATIC static
  12 #define EXTERN(type, name)
  13 #endif
  14
  15 /** Quick and dirty macros to implement test mocking.
  16  *
  17  * To use them, suppose that you have a function you'd like to mock
  18  * with the signature "void writebuf(size_t n, char *buf)".  You can then
  19  * declare the function as:
  20  *
  21  *     MOCK_DECL(void, writebuf, (size_t n, char *buf));
  22  *
  23  * and implement it as:
  24  *
  25  *     MOCK_IMPL(void,
  26  *     writebuf,(size_t n, char *buf))
  27  *     {
  28  *          ...
  29  *     }
  30  *
  31  * For the non-testing build, this will expand simply into:
  32  *
  33  *     void writebuf(size_t n, char *buf);
  34  *     void
  35  *     writebuf(size_t n, char *buf)
  36  *     {
  37  *         ...
  38  *     }
  39  *
  40  * But for the testing case, it will expand into:
  41  *
  42  *     void writebuf__real(size_t n, char *buf);
  43  *     extern void (*writebuf)(size_t n, char *buf);
  44  *
  45  *     void (*writebuf)(size_t n, char *buf) = writebuf__real;
  46  *     void
  47  *     writebuf__real(size_t n, char *buf)
  48  *     {
  49  *         ...
  50  *     }
  51  *
  52  * This is not a great mocking system!  It is deliberately "the simplest
  53  * thing that could work", and pays for its simplicity in its lack of
  54  * features, and in its uglification of the Tor code.  Replacing it with
  55  * something clever would be a fine thing.
  56  *
  57  * @{ */
  58 #ifdef TOR_UNIT_TESTS
  59 #define MOCK_DECL(rv, funcname, arglist)     \
  60   rv funcname ##__real arglist;              \
  61   extern rv(*funcname) arglist
  62 #define MOCK_IMPL(rv, funcname, arglist)     \
  63   rv(*funcname) arglist = funcname ##__real; \
  64   rv funcname ##__real arglist
  65 #define MOCK_DECL_ATTR(rv, funcname, arglist, attr) \
  66   rv funcname ##__real arglist attr;                \
  67   extern rv(*funcname) arglist
  68 #define MOCK_IMPL(rv, funcname, arglist)     \
  69   rv(*funcname) arglist = funcname ##__real; \
  70   rv funcname ##__real arglist
  71 #define MOCK(func, replacement)                 \
  72   do {                                          \
  73     (func) = (replacement);                     \
  74   } while (0)
  75 #define UNMOCK(func)                            \
  76   do {                                          \
  77     func = func ##__real;                       \
  78   } while (0)
  79 #else
  80 #define MOCK_DECL(rv, funcname, arglist) \
  81   rv funcname arglist
  82 #define MOCK_DECL_ATTR(rv, funcname, arglist, attr) \
  83   rv funcname arglist attr
  84 #define MOCK_IMPL(rv, funcname, arglist) \
  85   rv funcname arglist
  86 #endif
  87 /** @} */
  88
  89 #endif
  90