Disable color if TERM=dumb is detected

asottile · asottile · commit 120cae9d41b6 · 2019-07-27T13:46:30.000-07:00
diff --git a/pre_commit/color.py b/pre_commit/color.py
@@ -49,6 +49,10 @@ def use_color(setting):
         raise InvalidColorSetting(setting)
 
     return (
-        setting == 'always' or
-        (setting == 'auto' and sys.stdout.isatty() and terminal_supports_color)
+        setting == 'always' or (
+            setting == 'auto' and
+            sys.stdout.isatty() and
+            terminal_supports_color and
+            os.getenv('TERM') != 'dumb'
+        )
     )
diff --git a/tests/color_test.py b/tests/color_test.py
@@ -5,6 +5,7 @@
 import mock
 import pytest
 
+from pre_commit import envcontext
 from pre_commit.color import format_color
 from pre_commit.color import GREEN
 from pre_commit.color import InvalidColorSetting
@@ -38,13 +39,22 @@ def test_use_color_no_tty():
 def test_use_color_tty_with_color_support():
     with mock.patch.object(sys.stdout, 'isatty', return_value=True):
         with mock.patch('pre_commit.color.terminal_supports_color', True):
-            assert use_color('auto') is True
+            with envcontext.envcontext([('TERM', envcontext.UNSET)]):
+                assert use_color('auto') is True
 
 
 def test_use_color_tty_without_color_support():
     with mock.patch.object(sys.stdout, 'isatty', return_value=True):
         with mock.patch('pre_commit.color.terminal_supports_color', False):
-            assert use_color('auto') is False
+            with envcontext.envcontext([('TERM', envcontext.UNSET)]):
+                assert use_color('auto') is False
+
+
+def test_use_color_dumb_term():
+    with mock.patch.object(sys.stdout, 'isatty', return_value=True):
+        with mock.patch('pre_commit.color.terminal_supports_color', True):
+            with envcontext.envcontext([('TERM', 'dumb')]):
+                assert use_color('auto') is False
 
 
 def test_use_color_raises_if_given_shenanigans():
