Fix FORCE_COLOR and NO_COLOR when empty strings

Author: hugovk

Lib/_colorize.py

@@ -42,11 +42,11 @@ def can_colorize(*, file=None) -> bool:
             return False
         if os.environ.get("PYTHON_COLORS") == "1":
             return True
-    if "NO_COLOR" in os.environ:
+    if os.environ.get("NO_COLOR"):
         return False
     if not COLORIZE:
         return False
-    if "FORCE_COLOR" in os.environ:
+    if os.environ.get("FORCE_COLOR"):
         return True
     if os.environ.get("TERM") == "dumb":
         return False

Lib/test/test__colorize.py

@@ -48,17 +48,34 @@ def test_colorized_detection_checks_for_environment_variables(self):
                 ({"PYTHON_COLORS": "1"}, True),
                 ({"PYTHON_COLORS": "0"}, False),
                 ({"NO_COLOR": "1"}, False),
+                ({"NO_COLOR": "0"}, False),
                 ({"NO_COLOR": "1", "PYTHON_COLORS": "1"}, True),
                 ({"FORCE_COLOR": "1"}, True),
                 ({"FORCE_COLOR": "1", "NO_COLOR": "1"}, False),
+                ({"FORCE_COLOR": "1", "NO_COLOR": "0"}, False),
+                ({"FORCE_COLOR": "1", "NO_COLOR": ""}, True),
+                ({"FORCE_COLOR": "0", "NO_COLOR": "1"}, False),
+                ({"FORCE_COLOR": "", "NO_COLOR": "1"}, False),
                 ({"FORCE_COLOR": "1", "PYTHON_COLORS": "0"}, False),
+                ({"FORCE_COLOR": "0", "PYTHON_COLORS": "0"}, False),
             ]:
                 with self.subTest(env_vars=env_vars, expected=expected):
                     with unittest.mock.patch("os.environ", env_vars):
                         self.assertEqual(_colorize.can_colorize(), expected)
 
+            with unittest.mock.patch("os.environ", {"NO_COLOR": ""}):
+                if sys.platform == "win32":
+                    vt_mock.return_value = False
+                    self.assertEqual(_colorize.can_colorize(), False)
+
+                    vt_mock.return_value = True
+                    self.assertEqual(_colorize.can_colorize(), True)
+                else:
+                    self.assertEqual(_colorize.can_colorize(), True)
+
             with unittest.mock.patch("os.environ", {}):
                 if sys.platform == "win32":
+                    vt_mock.return_value = False
                     self.assertEqual(_colorize.can_colorize(), False)
 
                     vt_mock.return_value = True

Misc/NEWS.d/next/Library/2025-01-21-18-52-32.gh-issue-129061.4idD_B.rst

@@ -0,0 +1 @@
+Fix FORCE_COLOR and NO_COLOR when empty strings. Patch by Hugo van Kemenade.