utimens: Avoid test failures on macOS 10.13.

Reported by Martin Storsjö <martin@martin.st> in
<https://lists.gnu.org/archive/html/bug-gnulib/2020-12/msg00003.html>.

* tests/test-utimens-common.h (check_ctime): Define to -1 on macOS.
* tests/test-utimens.h (test_utimens): Don't expect a ctime change when
only the atime is requested to change.
* tests/test-futimens.h (test_futimens): Likewise.
* tests/test-lutimens.h (test_lutimens): Likewise.

4 files changed, 6 insertions, 3 deletions

diff --git a/tests/test-futimens.h b/tests/test-futimens.h
index 6a17013b68..31ff900f3d 100644
--- a/tests/test-futimens.h
+++ b/tests/test-futimens.h
@@ -166,7 +166,7 @@ test_futimens (int (*func) (int, struct timespec const *),
     ASSERT (get_stat_atime_ns (&st2) == 0);
     ASSERT (st3.st_mtime == st2.st_mtime);
     ASSERT (get_stat_mtime_ns (&st3) == get_stat_mtime_ns (&st2));
-    if (check_ctime)
+    if (check_ctime > 0)
       ASSERT (ctime_compare (&st3, &st2) < 0);
   }
 
diff --git a/tests/test-lutimens.h b/tests/test-lutimens.h
index f6d5586c20..589c9cfaaa 100644
--- a/tests/test-lutimens.h
+++ b/tests/test-lutimens.h
@@ -194,7 +194,7 @@ test_lutimens (int (*func) (char const *, struct timespec const *), bool print)
       }
     ASSERT (st3.st_mtime == st2.st_mtime);
     ASSERT (get_stat_mtime_ns (&st3) == get_stat_mtime_ns (&st2));
-    if (check_ctime)
+    if (check_ctime > 0)
       ASSERT (ctime_compare (&st3, &st2) < 0);
   }
 
diff --git a/tests/test-utimens-common.h b/tests/test-utimens-common.h
index 5861667fd4..3d665ef079 100644
--- a/tests/test-utimens-common.h
+++ b/tests/test-utimens-common.h
@@ -55,6 +55,9 @@ enum {
    properly tracked change time.  See
    <https://docs.microsoft.com/en-us/cpp/c-runtime-library/reference/stat-functions>.  */
 #  define check_ctime 0
+# elif defined __APPLE__ && defined __MACH__
+/* On macOS, the ctime is not updated when only the st_atime changes.  */
+#  define check_ctime -1
 # else
 #  define check_ctime 1
 # endif
diff --git a/tests/test-utimens.h b/tests/test-utimens.h
index c3c70297aa..9273fd07e0 100644
--- a/tests/test-utimens.h
+++ b/tests/test-utimens.h
@@ -145,7 +145,7 @@ test_utimens (int (*func) (char const *, struct timespec const *), bool print)
     ASSERT (get_stat_atime_ns (&st2) == 0);
     ASSERT (st3.st_mtime == st2.st_mtime);
     ASSERT (get_stat_mtime_ns (&st3) == get_stat_mtime_ns (&st2));
-    if (check_ctime)
+    if (check_ctime > 0)
       ASSERT (ctime_compare (&st3, &st2) < 0);
   }