bug: show original choice casing in invalid choice errors

lean/click.py

@@ -314,13 +314,22 @@ class CaseInsensitiveChoice(Choice):
     def __init__(self, choices, **kwargs):
         super().__init__(choices, case_sensitive=False, **kwargs)
 
-    def get_metavar(self, param, ctx=None) -> str:
+    def _get_display_choices(self) -> List[str]:
         import enum
-        choices_str = "|".join(c.value if isinstance(c, enum.Enum) else str(c) for c in self.choices)
+        return [c.value if isinstance(c, enum.Enum) else str(c) for c in self.choices]
+
+    def get_metavar(self, param, ctx=None) -> str:
+        choices_str = "|".join(self._get_display_choices())
         if param is not None and param.required and param.param_type_name == "argument":
             return f"{{{choices_str}}}"
         return f"[{choices_str}]"
 
+    def get_invalid_choice_message(self, value, ctx=None) -> str:
+        choices_str = ", ".join(map(repr, self._get_display_choices()))
+        if len(self.choices) == 1:
+            return f"{value!r} is not {choices_str}."
+        return f"{value!r} is not one of {choices_str}."
+
 
 class PathParameter(ParamType):
     """A limited version of click.Path which uses pathlib.Path."""

tests/test_click.py

@@ -22,7 +22,7 @@
 import pytest
 from click.testing import CliRunner
 
-from lean.click import DateParameter, LeanCommand, PathParameter, RegexParameter
+from lean.click import CaseInsensitiveChoice, DateParameter, LeanCommand, PathParameter, RegexParameter
 from lean.container import container
 from tests.test_helpers import create_fake_lean_cli_directory
 
@@ -257,3 +257,44 @@ def command(arg: str) -> None:
 
     assert result.exit_code != 0
     assert f"must match the '{TIME_REGEX}' format" in result.output
+
+
+def test_case_insensitive_choice_shows_original_casing_in_help() -> None:
+    @click.command()
+    @click.option("--brokerage", type=CaseInsensitiveChoice(["Paper Trading", "Interactive Brokers"]))
+    def command(brokerage: str) -> None:
+        pass
+
+    result = CliRunner().invoke(command, ["--help"])
+
+    assert result.exit_code == 0
+    assert "[Paper Trading|Interactive Brokers]" in result.output
+
+
+@pytest.mark.parametrize("input", ["Interactive Brokers", "interactive brokers", "INTERACTIVE BROKERS"])
+def test_case_insensitive_choice_returns_original_choice_regardless_of_input_casing(input: str) -> None:
+    given_brokerage: Optional[str] = None
+
+    @click.command()
+    @click.option("--brokerage", type=CaseInsensitiveChoice(["Paper Trading", "Interactive Brokers"]))
+    def command(brokerage: str) -> None:
+        nonlocal given_brokerage
+        given_brokerage = brokerage
+
+    result = CliRunner().invoke(command, ["--brokerage", input])
+
+    assert result.exit_code == 0
+
+    assert given_brokerage == "Interactive Brokers"
+
+
+def test_case_insensitive_choice_shows_original_casing_when_input_not_valid() -> None:
+    @click.command()
+    @click.option("--brokerage", type=CaseInsensitiveChoice(["Paper Trading", "Interactive Brokers"]))
+    def command(brokerage: str) -> None:
+        pass
+
+    result = CliRunner().invoke(command, ["--brokerage", "invalid"])
+
+    assert result.exit_code != 0
+    assert "'invalid' is not one of 'Paper Trading', 'Interactive Brokers'." in result.output