🐛 Fix preserving case in enum values

tests/test_enum_case.py

@@ -0,0 +1,34 @@
+"""
+Regresion test for
+    Enum values that differ in case get conflated #570
+    https://github.com/tiangolo/typer/discussions/570
+"""
+from enum import Enum
+
+import pytest
+import typer
+from typer.testing import CliRunner
+
+runner = CliRunner()
+app = typer.Typer()
+
+
+class Case(str, Enum):
+    UPPER = "CASE"
+    TITLE = "Case"
+    LOWER = "case"
+
+    def __str__(self) -> str:
+        return self.value
+
+
+@app.command()
+def enum_case(case: Case):
+    print(case)
+
+
+@pytest.mark.parametrize("case", Case)
+def test_enum_case(case: Case):
+    result = runner.invoke(app, [f"{case}"])
+    assert result.exit_code == 0
+    assert case in result.output

typer/main.py

@@ -618,13 +618,13 @@ def param_path_convertor(value: Optional[str] = None) -> Optional[Path]:
 
 
 def generate_enum_convertor(enum: Type[Enum]) -> Callable[[Any], Any]:
-    lower_val_map = {str(val.value).lower(): val for val in enum}
+    val_map = {str(val.value): val for val in enum}
 
     def convertor(value: Any) -> Any:
         if value is not None:
-            low = str(value).lower()
-            if low in lower_val_map:
-                key = lower_val_map[low]
+            val = str(value)
+            if val in val_map:
+                key = val_map[val]
                 return enum(key)
 
     return convertor