test_cmp expect actual
'
+test_expect_success 'diff --no-index allows external diff' '
+ test_expect_code 1 \
+ env GIT_EXTERNAL_DIFF="echo external ;:" \
+ git diff --no-index non/git/a non/git/b >actual &&
+ echo external >expect &&
+ test_cmp expect actual
+'
+
test_done