test/example/check: Reset times for regen tests

In principle, on a filesystem with poor time resolution, the updates
to the input files might have the same timestamp as the output files.
Things would then not be regenerated.

Work around this by resetting all timestamps in the build tree to
1s ago.  This should ensure that exactly the one file whose edit we
are simulating seems, to make, to have been changed.

There is a remaining possible problem: if our last actual change to
the subdirmk source tree is less than 1s ago, this might rebuild too
much.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

diff --git a/tests/example/check b/tests/example/check
index b7cf6dfd3a82d435a0fffc5fe761383af4d98e4f..143fe05dfe370b84398cbaad68f4488557570c8d 100755 (executable)
--- a/tests/example/check
+++ b/tests/example/check
@@ -26,12 +26,20 @@ make -j4 all check
 
 : ----- testing rebuild on input change -----
 
+reset_times () {
+       find -type f -print0 \
+       | xargs -0 \
+       touch -hmd 'now -1 seconds' --
+}
+
 : ----- for-check-1 -----
+reset_times
 echo 'for-check-1:' >>../src/for-test.sd.mk
 make -j4 for-check-1
 grep '^for-check-1:' src/Subdir.mk || false
 
 : ----- for-check-2 -----
+reset_times
 echo 'for-check-2:' >>../lib/for-test.mk.in
 make -j4 for-check-2
 grep '^for-check-2:' lib/for-test.mk || false