1 files changed, 51 insertions, 0 deletions
diff --git a/t/t4017-diff-retval.sh b/t/t4017-diff-retval.sh
index 68731908be..60dd2014d5 100755
--- a/t/t4017-diff-retval.sh
+++ b/t/t4017-diff-retval.sh
@@ -76,4 +76,55 @@ test_expect_success 'git diff-index --cached HEAD' '
 	}
 '
 
+test_expect_success '--check --exit-code returns 0 for no difference' '
+
+	git diff --check --exit-code
+
+'
+
+test_expect_success '--check --exit-code returns 1 for a clean difference' '
+
+	echo "good" > a &&
+	git diff --check --exit-code
+	test $? = 1
+
+'
+
+test_expect_success '--check --exit-code returns 3 for a dirty difference' '
+
+	echo "bad   " >> a &&
+	git diff --check --exit-code
+	test $? = 3
+
+'
+
+test_expect_success '--check with --no-pager returns 2 for dirty difference' '
+
+	git --no-pager diff --check
+	test $? = 2
+
+'
+
+
+test_expect_success 'check should test not just the last line' '
+	echo "" >>a &&
+	git --no-pager diff --check
+	test $? = 2
+
+'
+
+test_expect_success 'check detects leftover conflict markers' '
+	git reset --hard &&
+	git checkout HEAD^ &&
+	echo binary >>b &&
+	git commit -m "side" b &&
+	test_must_fail git merge master &&
+	git add b && (
+		git --no-pager diff --cached --check >test.out
+		test $? = 2
+	) &&
+	test 3 = $(grep "conflict marker" test.out | wc -l) &&
+	git reset --hard
+'
+
 test_done