Use autoconf to reliably get paths for test programs.

configure.ac

@@ -21,6 +21,9 @@ if test "x$ac_cv_prog_cc_c99" = xno; then
 fi
 AC_PROG_CPP
 
+# To get absolute paths in the vtc tests.
+AC_PATH_PROG([CAT], [cat], [])
+
 AX_PTHREAD(,[AC_MSG_ERROR([Could not configure pthreads support])])
 
 LIBS="$PTHREAD_LIBS $LIBS"

src/Makefile.am

@@ -29,7 +29,7 @@ AM_TESTS_ENVIRONMENT = \
 	LD_LIBRARY_PATH="$(VARNISH_LIBRARY_PATH)"
 TEST_EXTENSIONS = .vtc
 VTC_LOG_COMPILER = varnishtest -v
-AM_VTC_LOG_FLAGS = -Dvmod_pipe="$(VMOD_PIPE)"
+AM_VTC_LOG_FLAGS = -Dvmod_pipe="$(VMOD_PIPE)" -Dcat="$(CAT)"
 TESTS = @VMOD_TESTS@
 
 # To test an individual VTC test named test.vtc:

src/tests/vdp.vtc

@@ -45,7 +45,7 @@ varnish v1 -vcl+backend {
 	import ${vmod_pipe};
 
 	sub vcl_init {
-		new cat = pipe.vdp(name="cat", path="/bin/cat");
+		new cat = pipe.vdp(name="cat", path="${cat}");
 	}
 
 	sub vcl_backend_response {