t-strvec: use test_msg()

check_strvec_loc() checks each strvec item by looping through them and
comparing them with expected values.  If a check fails then we'd like
to know which item is affected.  It reports that information by building
a strbuf and delivering its contents using a failing assertion, e.g.
if there are fewer items in the strvec than expected:

   # check "vec->nr > nr" failed at t/unit-tests/t-strvec.c:19
   #    left: 1
   #   right: 1
   # check "strvec index 1" failed at t/unit-tests/t-strvec.c:71

Note that the index variable is "nr" and thus the interesting value is
reported twice in that example (in lines three and four).

Stop printing the index explicitly for checks that already report it.
The message for the same condition as above becomes:

   # check "vec->nr > nr" failed at t/unit-tests/t-strvec.c:19
   #    left: 1
   #   right: 1

For the string comparison, whose error message doesn't include the
index, report it using the simpler and more appropriate test_msg()
instead.  Report the index using its actual variable name and format the
line like the preceding ones.  The message for an unexpected string
value becomes:

   # check "!strcmp(vec->v[nr], str)" failed at t/unit-tests/t-strvec.c:24
   #    left: "foo"
   #   right: "bar"
   #      nr: 0

Reported-by: Phillip Wood <[email protected]>
Signed-off-by: René Scharfe <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: rscharfe

t/unit-tests/t-strvec.c

@@ -17,12 +17,12 @@ static void check_strvec_loc(const char *loc, struct strvec *vec, ...)
 			break;
 
 		if (!check_uint(vec->nr, >, nr) ||
-		    !check_uint(vec->alloc, >, nr) ||
-		    !check_str(vec->v[nr], str)) {
-			struct strbuf msg = STRBUF_INIT;
-			strbuf_addf(&msg, "strvec index %"PRIuMAX, (uintmax_t) nr);
-			test_assert(loc, msg.buf, 0);
-			strbuf_release(&msg);
+		    !check_uint(vec->alloc, >, nr)) {
+			va_end(ap);
+			return;
+		}
+		if (!check_str(vec->v[nr], str)) {
+			test_msg("     nr: %"PRIuMAX, (uintmax_t)nr);
 			va_end(ap);
 			return;
 		}