Avoid Colorama initialization in Git Bash on Windows

fire/formatting_windows.py

@@ -29,6 +29,10 @@
 
 def initialize_or_disable():
   """Enables ANSI processing on Windows or disables it as needed."""
+  # Git Bash's MinGW terminals already handle ANSI sequences. Initializing
+  # Colorama would unnecessarily wrap stdout and can interfere with colors.
+  if os.environ.get('MSYSTEM', '').upper().startswith(('MINGW', 'MSYS')):
+    return
   if HAS_COLORAMA:
     wrap = True
     if (hasattr(sys.stdout, 'isatty')

fire/formatting_windows_test.py

@@ -0,0 +1,55 @@
+# Copyright (C) 2026 Google LLC.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Tests for Windows ANSI initialization behavior."""
+
+from unittest import mock
+
+from fire import formatting_windows
+from fire import testutils
+
+
+class FormattingWindowsTest(testutils.BaseTestCase):
+
+  def test_git_bash_skips_colorama(self):
+    for msystem in ('MINGW64', 'MINGW32', 'MSYS', 'mingw64'):
+      with self.subTest(msystem=msystem):
+        with mock.patch.dict('os.environ', {'MSYSTEM': msystem}):
+          with mock.patch.object(formatting_windows, 'HAS_COLORAMA', True):
+            with mock.patch.object(formatting_windows, 'colorama',
+                                   create=True) as colorama:
+              with mock.patch.object(formatting_windows.platform, 'release',
+                                     side_effect=AssertionError('not needed')):
+                formatting_windows.initialize_or_disable()
+                colorama.init.assert_not_called()
+
+  def test_non_git_bash_keeps_colorama_initialization(self):
+    with mock.patch.dict('os.environ', {}, clear=True):
+      with mock.patch.object(formatting_windows, 'HAS_COLORAMA', True):
+        with mock.patch.object(formatting_windows, 'colorama',
+                               create=True) as colorama:
+          with mock.patch.object(formatting_windows.platform, 'release',
+                                 return_value='11'):
+            formatting_windows.initialize_or_disable()
+            colorama.init.assert_called_once_with(wrap=True)
+
+  def test_missing_colorama_disables_colors_outside_git_bash(self):
+    with mock.patch.dict('os.environ', {}, clear=True):
+      with mock.patch.object(formatting_windows, 'HAS_COLORAMA', False):
+        formatting_windows.initialize_or_disable()
+        self.assertEqual('1', formatting_windows.os.environ['ANSI_COLORS_DISABLED'])
+
+
+if __name__ == '__main__':
+  testutils.main()