tests: check that Git version are in sync

This ensures that the Git version pointed at by the submodule is the
same as the one that will be fetched using "make get-git".

Suggested-by: Ferry Huberts <ferry.huberts@pelagic.nl>
Signed-off-by: John Keeping <john@keeping.me.uk>

tests/t0001-validate-git-versions.sh

@@ -0,0 +1,36 @@
+#!/bin/sh
+
+. ./setup.sh
+
+prepare_tests 'Check Git version is correct'
+
+run_test 'extract Git version from Makefile' '
+	sed -n -e "/^GIT_VER[ 	]*=/ {
+		s/^GIT_VER[ 	]*=[ 	]*//
+		p
+	}" ../Makefile >trash/makefile_version
+'
+
+run_test 'test Git version matches Makefile' '
+	( cat ../git/GIT-VERSION-FILE || echo "No GIT-VERSION-FILE" ) |
+	sed -e "s/GIT_VERSION[ 	]*=[ 	]*//" >trash/git_version &&
+	diff -u trash/git_version trash/makefile_version
+'
+
+run_test 'test submodule version matches Makefile' '
+	if ! test -e ../git/.git
+	then
+		echo "git/ is not a Git repository" >&2
+	else
+		(
+			cd .. &&
+			sm_sha1=$(git ls-files --stage -- git |
+				sed -e "s/^[0-9]* \\([0-9a-f]*\\) [0-9]	.*$/\\1/") &&
+			cd git &&
+			git describe --match "v[0-9]*" $sm_sha1
+		) | sed -e "s/^v//" >trash/sm_version &&
+		diff -u trash/sm_version trash/makefile_version
+	fi
+'
+
+tests_done