Add unit tests for remove_inputs in InputObserver (#423)

* Initial plan

* Add unit tests for remove_inputs in InputObserver

Co-authored-by: xadupre <22452781+xadupre@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: xadupre <22452781+xadupre@users.noreply.github.com>

Author: Copilot

_unittests/ut_investigate/test_input_observer.py

@@ -1197,5 +1197,112 @@ def forward(self, a, *args, **kwargs):
             torch.export.export(model, args, kwargs=kwargs, dynamic_shapes=ds)
 
 
+    def test_remove_inputs_kwargs(self):
+        """Test that remove_inputs removes a kwarg from the observer info."""
+
+        class Model(torch.nn.Module):
+            def forward(self, x, y, z=None):
+                r = x + y
+                if z is not None:
+                    r += z
+                return r
+
+        inputs = [
+            dict(x=torch.randn((5, 6)), y=torch.randn((1, 6)), z=torch.randn((5, 6))),
+            dict(x=torch.randn((7, 7)), y=torch.randn((1, 7)), z=torch.randn((7, 7))),
+            dict(x=torch.randn((7, 8)), y=torch.randn((1, 8)), z=torch.randn((7, 8))),
+        ]
+
+        model = Model()
+        observer = InputObserver()
+        with observer(model):
+            for kwargs in inputs:
+                model(**kwargs)
+        self.assertEqual(len(observer.info), 3)
+
+        cst = torch.export.Dim.DYNAMIC
+        ds = observer.infer_dynamic_shapes()
+        self.assertIn("z", ds)
+        self.assertIn("x", ds)
+        self.assertIn("y", ds)
+
+        # Remove z input
+        observer.remove_inputs(["z"])
+
+        ds_after = observer.infer_dynamic_shapes()
+        self.assertNotIn("z", ds_after)
+        self.assertIn("x", ds_after)
+        self.assertIn("y", ds_after)
+        self.assertEqual(dict(x={0: cst, 1: cst}, y={1: cst}), ds_after)
+
+        args_after = observer.infer_arguments()
+        self.assertIsInstance(args_after, dict)
+        self.assertNotIn("z", args_after)
+        self.assertIn("x", args_after)
+        self.assertIn("y", args_after)
+
+    def test_remove_inputs_multiple_kwargs(self):
+        """Test that remove_inputs removes multiple kwargs at once."""
+
+        class Model(torch.nn.Module):
+            def forward(self, x, y, z=None, w=None):
+                r = x + y
+                if z is not None:
+                    r += z
+                if w is not None:
+                    r += w
+                return r
+
+        inputs = [
+            dict(
+                x=torch.randn((5, 6)),
+                y=torch.randn((1, 6)),
+                z=torch.randn((5, 6)),
+                w=torch.randn((1, 6)),
+            ),
+            dict(
+                x=torch.randn((6, 7)),
+                y=torch.randn((1, 7)),
+                z=torch.randn((6, 7)),
+                w=torch.randn((1, 7)),
+            ),
+            dict(
+                x=torch.randn((7, 8)),
+                y=torch.randn((1, 8)),
+                z=torch.randn((7, 8)),
+                w=torch.randn((1, 8)),
+            ),
+        ]
+
+        model = Model()
+        observer = InputObserver()
+        with observer(model):
+            for kwargs in inputs:
+                model(**kwargs)
+        self.assertEqual(len(observer.info), 3)
+
+        cst = torch.export.Dim.DYNAMIC
+        ds = observer.infer_dynamic_shapes()
+        self.assertIn("z", ds)
+        self.assertIn("w", ds)
+
+        # Remove z and w inputs
+        observer.remove_inputs(["z", "w"])
+
+        ds_after = observer.infer_dynamic_shapes()
+        self.assertNotIn("z", ds_after)
+        self.assertNotIn("w", ds_after)
+        self.assertIn("x", ds_after)
+        self.assertIn("y", ds_after)
+        self.assertEqual(dict(x={0: cst, 1: cst}, y={1: cst}), ds_after)
+
+        args_after = observer.infer_arguments()
+        self.assertIsInstance(args_after, dict)
+        self.assertNotIn("z", args_after)
+        self.assertNotIn("w", args_after)
+        self.assertIn("x", args_after)
+        self.assertIn("y", args_after)
+
+
 if __name__ == "__main__":
     unittest.main(verbosity=2)