Change libx52 mock tests to use preprocessor overrides

Prior to this change, libx52 tests needed a linker that supported the
--wrap argument. This is not available on OSX, and therefore, we had to
disable the unit tests on non-Linux systems.

Since we needed to rebuild the libx52 library anyway for the test, it is
simpler to just define libusb_control_transfer to point to our mock
function. This allows us to verify libx52 on all supported platforms.

configure.ac

@@ -73,11 +73,10 @@ AM_COND_IF([HAVE_DOXYGEN],
     [AC_CONFIG_FILES([Doxyfile])],
     [AC_MSG_WARN(["Doxygen not found; continuing without doxygen support"])])
 
-# cmocka unit tests, currently only supported on Linux
+# cmocka unit tests
 AX_PKG_CHECK_MODULES([CMOCKA], [cmocka >= 1.1], [], [have_cmocka=yes], [have_cmocka=no])
 AM_CONDITIONAL([HAVE_CMOCKA], [test "x$have_cmocka" = xyes])
-AM_COND_IF([HAVE_CMOCKA], [AM_COND_IF([LINUX], [],
-    [AC_MSG_WARN(["cmocka found; disabling mock tests on ${host_os}])])],
+AM_COND_IF([HAVE_CMOCKA], [],
     [AC_MSG_WARN(["cmocka not found; disabling unit test build"])])
 
 # Check for the presence of tm_gmtoff in struct tm. If we have this, then we

lib/libx52/Makefile.am

@@ -31,7 +31,6 @@ x52include_HEADERS = libx52.h
 # pkg-config files
 pkgconfig_DATA = libx52.pc
 
-if LINUX
 if HAVE_CMOCKA
 LOG_DRIVER = env AM_TAP_AWK='$(AWK)' $(SHELL) $(top_srcdir)/tap-driver.sh
 TESTS = libx52test
@@ -40,15 +39,14 @@ check_PROGRAMS = libx52test
 nodist_libx52test_SOURCES = test_libx52.c
 libx52test_SOURCES = $(libx52_la_SOURCES)
 libx52test_CFLAGS = @LIBUSB_CFLAGS@ -DLOCALEDIR='"$(localedir)"' -I $(top_srcdir)
-libx52test_CFLAGS += -DGENERATED_TESTS='"test_libx52.c"'
-libx52test_LDFLAGS = -Wl,--wrap=libusb_control_transfer @CMOCKA_LIBS@ @LIBUSB_LIBS@
+libx52test_CFLAGS += -Dlibusb_control_transfer=__wrap_libusb_control_transfer
+libx52test_LDFLAGS = @CMOCKA_LIBS@ @LIBUSB_LIBS@
 libx52test_LDADD = libx52.la
 
 CLEANFILES = test_libx52.c
 test_libx52.c: $(srcdir)/x52_test_gen.py $(srcdir)/x52_tests.json
 	$(AM_V_GEN) $(PYTHON) $(srcdir)/x52_test_gen.py $(srcdir)/x52_tests.json > $@
 endif
-endif
 
 # Extra files that need to be in the distribution
 EXTRA_DIST = libx52.h x52_commands.h x52_common.h README.md