Pass 'color' explicitly in error echoing

src/click/exceptions.py

@@ -3,6 +3,7 @@
 from gettext import ngettext
 
 from ._compat import get_text_stderr
+from .globals import resolve_color_default
 from .utils import echo
 from .utils import format_filename
 
@@ -29,6 +30,9 @@ class ClickException(Exception):
 
     def __init__(self, message: str) -> None:
         super().__init__(message)
+        # The context will be removed by the time we print the message, so cache
+        # the color settings here to be used later on (in `show`)
+        self.show_color: t.Optional[bool] = resolve_color_default()
         self.message = message
 
     def format_message(self) -> str:
@@ -41,7 +45,11 @@ def show(self, file: t.Optional[t.IO[t.Any]] = None) -> None:
         if file is None:
             file = get_text_stderr()
 
-        echo(_("Error: {message}").format(message=self.format_message()), file=file)
+        echo(
+            _("Error: {message}").format(message=self.format_message()),
+            file=file,
+            color=self.show_color,
+        )
 
 
 class UsageError(ClickException):

tests/test_testing.py

@@ -5,6 +5,7 @@
 import pytest
 
 import click
+from click.exceptions import ClickException
 from click.testing import CliRunner
 
 
@@ -199,6 +200,26 @@ def cli():
     assert not result.exception
 
 
+def test_with_color_errors():
+    class CLIError(ClickException):
+        def format_message(self) -> str:
+            return click.style(self.message, fg="red")
+
+    @click.command()
+    def cli():
+        raise CLIError("Red error")
+
+    runner = CliRunner()
+
+    result = runner.invoke(cli)
+    assert result.output == "Error: Red error\n"
+    assert result.exception
+
+    result = runner.invoke(cli, color=True)
+    assert result.output == f"Error: {click.style('Red error', fg='red')}\n"
+    assert result.exception
+
+
 def test_with_color_but_pause_not_blocking():
     @click.command()
     def cli():