Add test class helper to force no terminal colour

Author: hugovk

Lib/test/support/__init__.py

@@ -60,6 +60,7 @@
     "skip_on_s390x",
     "without_optimizer",
     "force_not_colorized",
+    "force_not_colorized_test_class",
     "BrokenIter",
     "in_systemd_nspawn_sync_suppressed",
     ]
@@ -2855,6 +2856,44 @@ def wrapper(*args, **kwargs):
     return wrapper
 
 
+
+def force_not_colorized_test_class(cls):
+    """Force the terminal not to be colorized."""
+    original_setup = cls.setUp
+    original_teardown = cls.tearDown
+
+    @functools.wraps(cls.setUp)
+    def setUp_wrapper(self, *args, **kwargs):
+        import _colorize
+
+        self._original_fn = _colorize.can_colorize
+        self._variables: dict[str, str | None] = {
+            "PYTHON_COLORS": None,
+            "FORCE_COLOR": None,
+            "NO_COLOR": None,
+        }
+        for key in self._variables:
+            self._variables[key] = os.environ.pop(key, None)
+        os.environ["NO_COLOR"] = "1"
+        _colorize.can_colorize = lambda: False
+        return original_setup(self, *args, **kwargs)
+
+    @functools.wraps(cls.tearDown)
+    def tearDown_wrapper(self, *args, **kwargs):
+        import _colorize
+
+        _colorize.can_colorize = self._original_fn
+        del os.environ["NO_COLOR"]
+        for key, value in self._variables.items():
+            if value is not None:
+                os.environ[key] = value
+        return original_teardown(self, *args, **kwargs)
+
+    cls.setUp = setUp_wrapper
+    cls.tearDown = tearDown_wrapper
+    return cls
+
+
 def initialized_with_pyrepl():
     """Detect whether PyREPL was used during Python initialization."""
     # If the main module has a __file__ attribute it's a Python module, which means PyREPL.

Lib/test/test_traceback.py

@@ -21,7 +21,7 @@
 from test.support.os_helper import TESTFN, unlink
 from test.support.script_helper import assert_python_ok, assert_python_failure
 from test.support.import_helper import forget
-from test.support import force_not_colorized
+from test.support import force_not_colorized, force_not_colorized_test_class
 
 import json
 import textwrap
@@ -1712,6 +1712,7 @@ def f():
 
 
 @requires_debug_ranges()
+@force_not_colorized_test_class
 class PurePythonTracebackErrorCaretTests(
     PurePythonExceptionFormattingMixin,
     TracebackErrorLocationCaretTestBase,
@@ -1725,6 +1726,7 @@ class PurePythonTracebackErrorCaretTests(
 
 @cpython_only
 @requires_debug_ranges()
+@force_not_colorized_test_class
 class CPythonTracebackErrorCaretTests(
     CAPIExceptionFormattingMixin,
     TracebackErrorLocationCaretTestBase,
@@ -1736,6 +1738,7 @@ class CPythonTracebackErrorCaretTests(
 
 @cpython_only
 @requires_debug_ranges()
+@force_not_colorized_test_class
 class CPythonTracebackLegacyErrorCaretTests(
     CAPIExceptionFormattingLegacyMixin,
     TracebackErrorLocationCaretTestBase,
@@ -2149,10 +2152,12 @@ def test_print_exception_bad_type_python(self):
 boundaries = re.compile(
     '(%s|%s)' % (re.escape(cause_message), re.escape(context_message)))
 
+@force_not_colorized_test_class
 class TestTracebackFormat(unittest.TestCase, TracebackFormatMixin):
     pass
 
 @cpython_only
+@force_not_colorized_test_class
 class TestFallbackTracebackFormat(unittest.TestCase, TracebackFormatMixin):
     DEBUG_RANGES = False
     def setUp(self) -> None:
@@ -2940,6 +2945,7 @@ def f():
         self.assertEqual(report, expected)
 
 
+@force_not_colorized_test_class
 class PyExcReportingTests(BaseExceptionReportingTests, unittest.TestCase):
     #
     # This checks reporting through the 'traceback' module, with both
@@ -2956,6 +2962,7 @@ def get_report(self, e):
         return s
 
 
+@force_not_colorized_test_class
 class CExcReportingTests(BaseExceptionReportingTests, unittest.TestCase):
     #
     # This checks built-in reporting by the interpreter.

Lib/test/test_unittest/test_result.py

@@ -1,14 +1,16 @@
 import io
 import sys
 import textwrap
-
-from test.support import warnings_helper, captured_stdout
-
 import traceback
 import unittest
-from unittest.util import strclass
-from test.support import force_not_colorized
+from test.support import (
+    captured_stdout,
+    force_not_colorized,
+    force_not_colorized_test_class,
+    warnings_helper,
+)
 from test.test_unittest.support import BufferedWriter
+from unittest.util import strclass
 
 
 class MockTraceback(object):
@@ -772,6 +774,7 @@ def testFoo(self):
         runner.run(Test('testFoo'))
 
 
+@force_not_colorized_test_class
 class TestOutputBuffering(unittest.TestCase):
 
     def setUp(self):