tests: make sure rename pretty print works

Add basic use cases and corner cases tests for
"git diff -M --summary/stat".

Signed-off-by: Antoine Pelisse <apelisse@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t4001-diff-rename.sh

@@ -102,4 +102,58 @@ test_expect_success 'setup for many rename source candidates' '
 	grep warning actual.err
 '
 
+test_expect_success 'rename pretty print with nothing in common' '
+	mkdir -p a/b/ &&
+	: >a/b/c &&
+	git add a/b/c &&
+	git commit -m "create a/b/c" &&
+	mkdir -p c/b/ &&
+	git mv a/b/c c/b/a &&
+	git commit -m "a/b/c -> c/b/a" &&
+	git diff -M --summary HEAD^ HEAD >output &&
+	test_i18ngrep " a/b/c => c/b/a " output &&
+	git diff -M --stat HEAD^ HEAD >output &&
+	test_i18ngrep " a/b/c => c/b/a " output
+'
+
+test_expect_success 'rename pretty print with common prefix' '
+	mkdir -p c/d &&
+	git mv c/b/a c/d/e &&
+	git commit -m "c/b/a -> c/d/e" &&
+	git diff -M --summary HEAD^ HEAD >output &&
+	test_i18ngrep " c/{b/a => d/e} " output &&
+	git diff -M --stat HEAD^ HEAD >output &&
+	test_i18ngrep " c/{b/a => d/e} " output
+'
+
+test_expect_success 'rename pretty print with common suffix' '
+	mkdir d &&
+	git mv c/d/e d/e &&
+	git commit -m "c/d/e -> d/e" &&
+	git diff -M --summary HEAD^ HEAD >output &&
+	test_i18ngrep " {c/d => d}/e " output &&
+	git diff -M --stat HEAD^ HEAD >output &&
+	test_i18ngrep " {c/d => d}/e " output
+'
+
+test_expect_success 'rename pretty print with common prefix and suffix' '
+	mkdir d/f &&
+	git mv d/e d/f/e &&
+	git commit -m "d/e -> d/f/e" &&
+	git diff -M --summary HEAD^ HEAD >output &&
+	test_i18ngrep " d/{ => f}/e " output &&
+	git diff -M --stat HEAD^ HEAD >output &&
+	test_i18ngrep " d/{ => f}/e " output
+'
+
+test_expect_success 'rename pretty print common prefix and suffix overlap' '
+	mkdir d/f/f &&
+	git mv d/f/e d/f/f/e &&
+	git commit -m "d/f/e d/f/f/e" &&
+	git diff -M --summary HEAD^ HEAD >output &&
+	test_i18ngrep " d/f/{ => f}/e " output &&
+	git diff -M --stat HEAD^ HEAD >output &&
+	test_i18ngrep " d/f/{ => f}/e " output
+'
+
 test_done