feat(tracing): add test for extra args passed to ufuncs

- add comment to explain why sanitizing all args is safe for ufuncs

concrete/numpy/tracing.py

@@ -34,7 +34,7 @@ class NPTracer(BaseTracer):
 
     _mix_values_func: Callable[..., BaseValue] = mix_values_determine_holding_dtype
 
-    def __array_ufunc__(self, ufunc, method, *input_tracers, **kwargs):
+    def __array_ufunc__(self, ufunc: numpy.ufunc, method, *args, **kwargs):
         """Catch calls to numpy ufunc and routes them to tracing functions if supported.
 
         Read more: https://numpy.org/doc/stable/user/basics.dispatch.html#basics-dispatch
@@ -43,11 +43,13 @@ class NPTracer(BaseTracer):
             tracing_func = self.get_tracing_func_for_np_function(ufunc)
             custom_assert(
                 (len(kwargs) == 0),
-                f"**kwargs are currently not supported for numpy ufuncs, ufunc: {ufunc}",
+                f"**kwargs are currently not supported for numpy ufuncs, ufunc: {ufunc.__name__}",
             )
-            # Create constant tracers when needed
-            sanitized_input_tracers = [self._sanitize(inp) for inp in input_tracers]
-            return tracing_func(*sanitized_input_tracers, **kwargs)
+
+            # Create constant tracers for args, numpy only passes ufunc.nin args so we can
+            # sanitize all of them without issues
+            sanitized_args = [self._sanitize(arg) for arg in args]
+            return tracing_func(*sanitized_args, **kwargs)
         raise NotImplementedError("Only __call__ method is supported currently")
 
     def __array_function__(self, func, _types, args, kwargs):

tests/numpy/test_tracing.py

@@ -462,6 +462,40 @@ def test_trace_numpy_ufuncs_not_supported():
     assert "Only __call__ method is supported currently" in str(excinfo.value)
 
 
+def test_trace_numpy_ufuncs_no_kwargs_no_extra_args():
+    """Test a case where kwargs are not allowed and too many inputs are passed"""
+    inputs = {
+        "x": EncryptedScalar(Integer(32, is_signed=True)),
+        "y": EncryptedScalar(Integer(32, is_signed=True)),
+        "z": EncryptedScalar(Integer(32, is_signed=True)),
+    }
+
+    # We really need a lambda (because numpy functions are not playing
+    # nice with inspect.signature), but pylint and flake8 are not happy
+    # with it
+    # pylint: disable=unnecessary-lambda
+    function_to_trace = lambda x, y, z: numpy.add(x, y, z)  # noqa: E731
+    # pylint: enable=unnecessary-lambda
+
+    with pytest.raises(AssertionError) as excinfo:
+        tracing.trace_numpy_function(function_to_trace, inputs)
+
+    # numpy only passes ufunc.nin tracers so the extra arguments are passed as kwargs
+    assert "**kwargs are currently not supported for numpy ufuncs, ufunc: add" in str(excinfo.value)
+
+    # We really need a lambda (because numpy functions are not playing
+    # nice with inspect.signature), but pylint and flake8 are not happy
+    # with it
+    # pylint: disable=unnecessary-lambda
+    function_to_trace = lambda x, y, z: numpy.add(x, y, out=z)  # noqa: E731
+    # pylint: enable=unnecessary-lambda
+
+    with pytest.raises(AssertionError) as excinfo:
+        tracing.trace_numpy_function(function_to_trace, inputs)
+
+    assert "**kwargs are currently not supported for numpy ufuncs, ufunc: add" in str(excinfo.value)
+
+
 @pytest.mark.parametrize(
     "function_to_trace,inputs,expected_output_node,expected_output_value",
     [