fix: Optional non-variadic tuple should be allowed (None shouldnt fai…

…l arity check).

CHANGELOG.md

@@ -5,6 +5,7 @@
 ### 0.24.2
 
 - fix: Literal contained inside non-variadic tuple should not imply "choices".
+- fix: Optional non-variadic tuple should be allowed (None shouldn't fail arity check).
 
 ### 0.24.1
 

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "cappa"
-version = "0.24.1"
+version = "0.24.2"
 description = "Declarative CLI argument parser."
 
 urls = {repository = "https://github.com/dancardin/cappa"}

src/cappa/arg.py

@@ -522,6 +522,9 @@ def infer_num_args(
         distinct_num_args = set()
         num_args_variants = []
         for type_arg in type_view.inner_types:
+            if type_arg.is_none_type:
+                continue
+
             num_args = infer_num_args(
                 arg,
                 type_arg,

tests/arg/test_tuple.py

@@ -53,3 +53,38 @@ class Example:
         parse(Example, "-s", "1", "2", "3", backend=backend)
     assert e.value.code == 2
     assert str(e.value.message).lower() == "unrecognized arguments: 3"
+
+
+@backends
+def test_optional_tuple_option(backend):
+    @dataclass
+    class Example:
+        start_project: Annotated[
+            tuple[int, float] | None,
+            cappa.Arg(short=True, required=False),
+        ] = None
+
+    test = parse(Example, backend=backend)
+    assert test == Example(start_project=None)
+
+    test = parse(Example, "-s", "2", "2.4", backend=backend)
+    assert test == Example(start_project=(2, 2.4))
+
+    # Missing values
+    with pytest.raises(cappa.Exit) as e:
+        parse(Example, "-s", "1", backend=backend)
+
+    assert e.value.code == 2
+
+    if backend:
+        assert str(e.value.message).lower() == "argument -s: expected 2 arguments"
+    else:
+        assert (
+            e.value.message == "Argument '-s' requires 2 values, found 1 ('1' so far)"
+        )
+
+    # Extra values
+    with pytest.raises(cappa.Exit) as e:
+        parse(Example, "-s", "1", "2", "3", backend=backend)
+    assert e.value.code == 2
+    assert str(e.value.message).lower() == "unrecognized arguments: 3"