help: use parseopt

diff --git a/t/t4020-diff-external.sh b/t/t4020-diff-external.sh
index f0045cd788a275f525bbd94912c5ad09cf6226bd..888293361d4ec39e389b321493dac8ed08886d7c 100755 (executable)
--- a/t/t4020-diff-external.sh
+++ b/t/t4020-diff-external.sh
@@ -94,4 +94,16 @@ test_expect_success 'diff attribute should apply only to diff' '
 
 '
 
+test_expect_success 'no diff with -diff' '
+       echo >.gitattributes "file -diff" &&
+       git diff | grep Binary
+'
+
+echo NULZbetweenZwords | tr Z '\000' > file
+
+test_expect_success 'force diff with "diff"' '
+       echo >.gitattributes "file diff" &&
+       git diff | grep -a second
+'
+
 test_done