tests: add a testcase for "git submodule sync"

This testcase ensures that upstream changes to submodule properties
can be updated using the sync subcommand.  This particular test
changes the submodule URL upstream and uses the sync command to update
an existing checkout.

Signed-off-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Shawn O. Pearce <spearce@spearce.org>

t/t7403-submodule-sync.sh

@@ -0,0 +1,64 @@
+#!/bin/sh
+#
+# Copyright (c) 2008 David Aguilar
+#
+
+test_description='git submodule sync
+
+These tests exercise the "git submodule sync" subcommand.
+'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+	echo file > file &&
+	git add file &&
+	test_tick &&
+	git commit -m upstream
+	git clone . super &&
+	git clone super submodule &&
+	(cd super &&
+	 git submodule add ../submodule submodule &&
+	 test_tick &&
+	 git commit -m "submodule"
+	) &&
+	git clone super super-clone &&
+	(cd super-clone && git submodule update --init)
+'
+
+test_expect_success 'change submodule' '
+	(cd submodule &&
+	 echo second line >> file &&
+	 test_tick &&
+	 git commit -a -m "change submodule"
+	)
+'
+
+test_expect_success 'change submodule url' '
+	(cd super &&
+	 cd submodule &&
+	 git checkout master &&
+	 git pull
+	) &&
+	mv submodule moved-submodule &&
+	(cd super &&
+	 git config -f .gitmodules submodule.submodule.url ../moved-submodule
+	 test_tick &&
+	 git commit -a -m moved-submodule
+	)
+'
+
+test_expect_success '"git submodule sync" should update submodule URLs' '
+	(cd super-clone &&
+	 git pull &&
+	 git submodule sync
+	) &&
+	test -d "$(git config -f super-clone/submodule/.git/config \
+	                        remote.origin.url)" &&
+	(cd super-clone/submodule &&
+	 git checkout master &&
+	 git pull
+	)
+'
+
+test_done