gh-129061: Fix FORCE_COLOR and NO_COLOR when empty strings (#129140)

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

@@ -44,8 +44,10 @@ def check(env, fallback, expected):
                 check({'TERM': ''}, fallback, fallback)
                 check({'FORCE_COLOR': '1'}, fallback, True)
                 check({'FORCE_COLOR': '0'}, fallback, True)
+                check({'FORCE_COLOR': ''}, fallback, fallback)
                 check({'NO_COLOR': '1'}, fallback, False)
                 check({'NO_COLOR': '0'}, fallback, False)
+                check({'NO_COLOR': ''}, fallback, fallback)
 
             check({'TERM': 'dumb', 'FORCE_COLOR': '1'}, False, True)
             check({'FORCE_COLOR': '1', 'NO_COLOR': '1'}, True, False)

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.