Add t7506 to test submodule related functions for git-status

Signed-off-by: Ping Yin <pkufranky@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4027-diff-submodule.sh

@@ -50,7 +50,7 @@ test_expect_success 'git diff-files --raw' '
 	test_cmp expect actual.files
 '
 
-test_expect_success 'git diff (empty submodule dir)' '
+test_expect_failure 'git diff (empty submodule dir)' '
 	: >empty &&
 	rm -rf sub/* sub/.git &&
 	git diff > actual.empty &&

t/t7506-status-submodule.sh

@@ -0,0 +1,38 @@
+#!/bin/sh
+
+test_description='git-status for submodule'
+
+. ./test-lib.sh
+
+test_expect_success 'setup' '
+	test_create_repo sub
+	cd sub &&
+	: >bar &&
+	git add bar &&
+	git commit -m " Add bar" &&
+	cd .. &&
+	git add sub &&
+	git commit -m "Add submodule sub"
+'
+
+test_expect_success 'status clean' '
+	git status |
+	grep "nothing to commit"
+'
+test_expect_success 'status -a clean' '
+	git status -a |
+	grep "nothing to commit"
+'
+test_expect_success 'rm submodule contents' '
+	rm -rf sub/* sub/.git
+'
+test_expect_success 'status clean (empty submodule dir)' '
+	git status |
+	grep "nothing to commit"
+'
+test_expect_failure 'status -a clean (empty submodule dir)' '
+	git status -a |
+	grep "nothing to commit"
+'
+
+test_done