Detect missing typehint early

src/sciline/_provider.py

@@ -125,7 +125,7 @@ def deduce_key(self) -> Any:
         """Attempt to determine the key (return type) of the provider."""
         if (key := get_type_hints(self._func).get('return')) is None:
             raise ValueError(
-                f'Provider {self} lacks type-hint for return value or returns NOne.'
+                f'Provider {self} lacks type-hint for return value or returns None.'
             )
         return key
 
@@ -175,8 +175,13 @@ def from_function(cls, provider: ToProvider) -> ArgSpec:
         """Parse the argument spec of a provider."""
         hints = get_type_hints(provider)
         signature = inspect.getfullargspec(provider)
-        args = {name: hints[name] for name in signature.args}
-        kwargs = {name: hints[name] for name in signature.kwonlyargs}
+        try:
+            args = {name: hints[name] for name in signature.args}
+            kwargs = {name: hints[name] for name in signature.kwonlyargs}
+        except KeyError:
+            raise ValueError(
+                f'Provider {provider} lacks type-hint for arguments.'
+            ) from None
         return cls(args=args, kwargs=kwargs)
 
     @classmethod

tests/pipeline_test.py

@@ -1250,3 +1250,19 @@ def func(*, a: G[A]) -> int:
 
     pipeline = sl.Pipeline([func], params={G[A]: 3, G[B]: 4})
     assert pipeline.compute(int, scheduler=scheduler) == -12
+
+
+def test_pipeline_detect_missing_argument_typehint() -> None:
+    def f(x) -> int:  # type: ignore[no-untyped-def]
+        return x  # type:ignore[no-any-return]
+
+    with pytest.raises(ValueError, match='type-hint'):
+        sl.Pipeline([f])
+
+
+def test_pipeline_detect_missing_return_typehint() -> None:
+    def f(x: int):  # type: ignore[no-untyped-def]
+        return x
+
+    with pytest.raises(ValueError, match='type-hint'):
+        sl.Pipeline([f])