From 172a496132fa367aa10a19baae8abbf1378fb9bd Mon Sep 17 00:00:00 2001
From: Vishwas B Sharma <sharma.vishwas88@gmail.com>
Date: Sat, 21 Apr 2018 01:53:28 -0700
Subject: [PATCH] [#149] Make check and diff not mutually exclusive

---
 black.py            | 6 +-----
 tests/test_black.py | 9 +++++++++
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/black.py b/black.py
index 49a5729f588..f9e048f104f 100644
--- a/black.py
+++ b/black.py
@@ -184,12 +184,8 @@ def main(
             sources.append(Path("-"))
         else:
             err(f"invalid path: {s}")
-    if check and diff:
-        exc = click.ClickException("Options --check and --diff are mutually exclusive")
-        exc.exit_code = 2
-        raise exc
 
-    if check:
+    if check and not diff:
         write_back = WriteBack.NO
     elif diff:
         write_back = WriteBack.DIFF
diff --git a/tests/test_black.py b/tests/test_black.py
index fc310690cce..2e1c6416b61 100644
--- a/tests/test_black.py
+++ b/tests/test_black.py
@@ -595,6 +595,15 @@ def test_write_cache_write_fail(self) -> None:
             mock.side_effect = OSError
             black.write_cache({}, [])
 
+    def test_check_diff_use_together(self) -> None:
+        with cache_dir() as workspace:
+            src = (workspace / "test.py").resolve()
+            with src.open("w") as fobj:
+                fobj.write("print('hello_bad_indented')")
+            result = CliRunner().invoke(black.main, [str(src), "--diff", "--check"])
+            self.assertEqual(result.exit_code, 0)
+            self.assertFalse(black.CACHE_FILE.exists())
+
 
 if __name__ == "__main__":
     unittest.main()