Controlling Color

The Python interpreter is configured by default to use colors to highlight

output in certain situations such as when displaying tracebacks. This

behavior can be controlled by setting different environment variables.

Setting the environment variable ``TERM`` to ``dumb`` will disable color.

If the environment variable ``FORCE_COLOR`` is set, then color will be

enabled regardless of the value of TERM. This is useful on CI systems which

aren’t terminals but can none-the-less display ANSI escape sequences.

If the environment variable ``NO_COLOR`` is set, Python will disable all color

in the output. This takes precedence over ``FORCE_COLOR``.

All these environment variables are used also by other tools to control color

output. To control the color output only in the Python interpreter, the

:envvar:`PY_COLORS` environment variable can be used. This variable takes

less precedence than ``NO_COLOR`` and ``FORCE_COLOR``.

with unittest.mock.patch("nt._supports_virtual_terminal", return_value=True):

with unittest.mock.patch("os.isatty") as isatty_mock:

isatty_mock.return_value = True

with unittest.mock.patch("os.environ", {'TERM': 'dumb'}):

self.assertEqual(traceback._can_colorize(), False)

with unittest.mock.patch("os.environ", {'PY_COLORS': '1'}):

self.assertEqual(traceback._can_colorize(), True)

with unittest.mock.patch("os.environ", {'PY_COLORS': '0'}):

self.assertEqual(traceback._can_colorize(), False)

with unittest.mock.patch("os.environ", {'NO_COLOR': '1'}):

self.assertEqual(traceback._can_colorize(), False)

with unittest.mock.patch("os.environ", {'NO_COLOR': '1', "PY_COLORS": '1'}):

self.assertEqual(traceback._can_colorize(), False)

with unittest.mock.patch("os.environ", {'FORCE_COLOR': '1'}):

self.assertEqual(traceback._can_colorize(), True)

with unittest.mock.patch("os.environ", {'FORCE_COLOR': '1', 'NO_COLOR': '1'}):

self.assertEqual(traceback._can_colorize(), False)

isatty_mock.return_value = False