tests: move copy/pasted PERL + Test::More checks to a lib-perl.sh

Since the original "perl -MTest::More" prerequisite check was added in
[1] it's been copy/pasted in [2], [3] and [4]. As we'll be changing
these codepaths in a subsequent commit let's consolidate these.

While we're at it let's move these to a lazy prereq, and make them
conform to our usual coding style (e.g. "\nthen", not "; then").

1. e46f9c8161a (t9700: skip when Test::More is not available,
   2008-06-29)
2. 5e9637c6297 (i18n: add infrastructure for translating Git with
   gettext, 2011-11-18)
3. 8d314d7afec (send-email: reduce dependencies impact on
   parse_address_line, 2015-07-07)
4. f07eeed123b (git-credential-netrc: adapt to test framework for git,
   2018-05-12)

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/t/lib-perl.sh b/t/lib-perl.sh
new file mode 100644
index 0000000000..d0bf509a16
--- /dev/null
+++ b/t/lib-perl.sh
@@ -0,0 +1,19 @@
+# Copyright (c) 2022 Ævar Arnfjörð Bjarmason
+
+test_lazy_prereq PERL_TEST_MORE '
+	perl -MTest::More -e 0
+'
+
+skip_all_if_no_Test_More () {
+	if ! test_have_prereq PERL
+	then
+		skip_all='skipping perl interface tests, perl not available'
+		test_done
+	fi
+
+	if ! test_have_prereq PERL_TEST_MORE
+	then
+		skip_all="Perl Test::More unavailable, skipping test"
+		test_done
+	fi
+}