[PATCH] t4212: handle systems with post-apocalyptic gmtime

[Jeff King <peff@peff.net>]

One of the tests in t4212 checks our behavior when we feed
gmtime a date so far in the future that it gives up and
returns NULL.

But some gmtime implementations just refuse to quit. They
soldier on, giving us a glimpse of a chilly October evening
some 160 million years in the future (and presumably filled
with our leather-clad horseback-riding ape descendants).

Let's allow the test to match either the sentinel value
(i.e., what we want when gmtime gives up) or any reasonable
value returned by known implementations.

Reported-by: Charles Bailey <cbailey32@bloomberg.net>
Signed-off-by: Jeff King <peff@peff.net>
---
On top of jk/commit-dates-parsing-fix (though the test is already in
v1.9.1).

 t/t4212-log-corrupt.sh | 23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/t/t4212-log-corrupt.sh b/t/t4212-log-corrupt.sh
index 85c6df4..08f982c 100755
--- a/t/t4212-log-corrupt.sh
+++ b/t/t4212-log-corrupt.sh
@@ -76,12 +76,27 @@ test_expect_success 'date parser recognizes time_t overflow' '
 	test_cmp expect actual
 '
 
-# date is within 2^63-1, but enough to choke glibc's gmtime
-test_expect_success 'absurdly far-in-future dates produce sentinel' '
+cmp_one_of () {
+	for candidate in "$@"; do
+		echo "$candidate" >expect &&
+		test_cmp expect actual &&
+		return 0
+	done
+	return 1
+}
+
+# date is within 2^63-1, but enough to choke glibc's gmtime.
+# We check that either the date broke gmtime (and we return the
+# usual epoch value), or gmtime gave us some sensible value.
+#
+# The sensible values are determined experimentally. The first
+# is from AIX.
+test_expect_success 'absurdly far-in-future dates' '
 	commit=$(munge_author_date HEAD 999999999999999999) &&
-	echo "Thu Jan 1 00:00:00 1970 +0000" >expect &&
 	git log -1 --format=%ad $commit >actual &&
-	test_cmp expect actual
+	cmp_one_of \
+		"Thu Jan 1 00:00:00 1970 +0000" \
+		"Thu Oct 24 18:46:39 162396404 -0700"
 '
 
 test_done
-- 
1.9.1.656.ge8a0637