Use red text when printing errors on command line

mypy.ini

@@ -18,6 +18,10 @@ warn_return_any = True
 no_implicit_reexport = True
 strict_equality = True
 
+[mypy-colorama]
+; https://github.com/tartley/colorama/issues/206
+ignore_missing_imports = True
+
 [mypy-importlib_metadata]
 ; https://gitlab.com/python-devs/importlib_metadata/-/issues/10
 ignore_missing_imports = True

setup.cfg

@@ -43,6 +43,7 @@ install_requires=
     importlib_metadata; python_version < "3.8"
     keyring >= 15.1
     rfc3986 >= 1.4.0
+    colorama >= 0.4.3
 setup_requires =
     setuptools_scm >= 1.15
 include_package_data = True

tests/test_main.py

@@ -10,14 +10,20 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-import pretend
+import sys
+
+import colorama
 
 from twine import __main__ as dunder_main
-from twine import cli
-from twine import exceptions
 
 
 def test_exception_handling(monkeypatch):
-    replaced_dispatch = pretend.raiser(exceptions.InvalidConfiguration("foo"))
-    monkeypatch.setattr(cli, "dispatch", replaced_dispatch)
-    assert dunder_main.main() == "InvalidConfiguration: foo"
+    monkeypatch.setattr(sys, "argv", ["twine", "upload", "missing.whl"])
+    message = "InvalidDistribution: Cannot find file (or expand pattern): 'missing.whl'"
+    assert dunder_main.main() == colorama.Fore.RED + message + colorama.Style.RESET_ALL
+
+
+def test_no_color_exception(monkeypatch):
+    monkeypatch.setattr(sys, "argv", ["twine", "--no-color", "upload", "missing.whl"])
+    message = "InvalidDistribution: Cannot find file (or expand pattern): 'missing.whl'"
+    assert dunder_main.main() == message

tox.ini

@@ -11,6 +11,7 @@ deps =
     portend
     pytest-services
     munch
+    colorama
 passenv =
     PYTEST_ADDOPTS
 commands =

twine/__main__.py

@@ -15,6 +15,7 @@
 import sys
 from typing import Any
 
+import colorama
 import requests
 
 from twine import cli
@@ -25,7 +26,16 @@ def main() -> Any:
     try:
         return cli.dispatch(sys.argv[1:])
     except (exceptions.TwineException, requests.HTTPError) as exc:
-        return "{}: {}".format(exc.__class__.__name__, exc.args[0])
+        return _format_error(f"{exc.__class__.__name__}: {exc.args[0]}")
+
+
+def _format_error(message: str) -> str:
+    pre_style, post_style = "", ""
+    if not cli.args.no_color:
+        colorama.init()
+        pre_style, post_style = colorama.Fore.RED, colorama.Style.RESET_ALL
+
+    return f"{pre_style}{message}{post_style}"
 
 
 if __name__ == "__main__":

twine/cli.py

@@ -27,6 +27,8 @@
 import twine
 from twine import _installed
 
+args = argparse.Namespace()
+
 
 def _registered_commands(
     group: str = "twine.registered_commands",
@@ -59,14 +61,21 @@ def dispatch(argv: List[str]) -> Any:
         action="version",
         version="%(prog)s version {} ({})".format(twine.__version__, dep_versions()),
     )
+    parser.add_argument(
+        "--no-color",
+        default=False,
+        required=False,
+        action="store_true",
+        help="disable colored output",
+    )
     parser.add_argument(
         "command", choices=registered_commands.keys(),
     )
     parser.add_argument(
         "args", help=argparse.SUPPRESS, nargs=argparse.REMAINDER,
     )
 
-    args = parser.parse_args(argv)
+    parser.parse_args(argv, namespace=args)
 
     main = registered_commands[args.command].load()