1 files changed, 29 insertions, 0 deletions
diff --git a/t/t4022-diff-rewrite.sh b/t/t4022-diff-rewrite.sh
new file mode 100755
index 0000000000..2a537a21e8
--- /dev/null
+++ b/t/t4022-diff-rewrite.sh
@@ -0,0 +1,29 @@
+#!/bin/sh
+
+test_description='rewrite diff'
+
+. ./test-lib.sh
+
+test_expect_success setup '
+
+	cat "$TEST_DIRECTORY"/../COPYING >test &&
+	git add test &&
+	tr \
+	  "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" \
+	  "nopqrstuvwxyzabcdefghijklmNOPQRSTUVWXYZABCDEFGHIJKLM" \
+	  <"$TEST_DIRECTORY"/../COPYING >test
+
+'
+
+test_expect_success 'detect rewrite' '
+
+	actual=$(git diff-files -B --summary test) &&
+	expr "$actual" : " rewrite test ([0-9]*%)$" || {
+		echo "Eh? <<$actual>>"
+		false
+	}
+
+'
+
+test_done
+