🐛 Add support for an argument of type Optional[Tuple] and default v…

…alue `None` (#757)

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: svlandeg <svlandeg@github.com>

tests/test_type_conversion.py

@@ -29,6 +29,25 @@ def opt(user: Optional[str] = None):
     assert "User: Camila" in result.output
 
 
+def test_optional_tuple():
+    app = typer.Typer()
+
+    @app.command()
+    def opt(number: Optional[Tuple[int, int]] = None):
+        if number:
+            print(f"Number: {number}")
+        else:
+            print("No number")
+
+    result = runner.invoke(app)
+    assert result.exit_code == 0
+    assert "No number" in result.output
+
+    result = runner.invoke(app, ["--number", "4", "2"])
+    assert result.exit_code == 0
+    assert "Number: (4, 2)" in result.output
+
+
 def test_no_type():
     app = typer.Typer()
 

typer/main.py

@@ -645,10 +645,14 @@ def internal_convertor(value: Sequence[Any]) -> Optional[List[Any]]:
 
 def generate_tuple_convertor(
     types: Sequence[Any],
-) -> Callable[[Tuple[Any, ...]], Tuple[Any, ...]]:
+) -> Callable[[Optional[Tuple[Any, ...]]], Optional[Tuple[Any, ...]]]:
     convertors = [determine_type_convertor(type_) for type_ in types]
 
-    def internal_convertor(param_args: Tuple[Any, ...]) -> Tuple[Any, ...]:
+    def internal_convertor(
+        param_args: Optional[Tuple[Any, ...]],
+    ) -> Optional[Tuple[Any, ...]]:
+        if param_args is None:
+            return None
         return tuple(
             convertor(arg) if convertor else arg
             for (convertor, arg) in zip(convertors, param_args)