Fix codecov by raising UnsupportedError (pytorch#1662)

Summary:
Pull Request resolved: pytorch#1662

Codecov is failing: https://app.codecov.io/gh/pytorch/botorch/commit/2f2b7e2163186e47da82b2da54b2fb0f001d9a7f

Reviewed By: Balandat

Differential Revision: D43120342

fbshipit-source-id: ea0c6ca035f6fcf116ecb1305d7367a9df55d48f

test/optim/test_parameter_constraints.py

@@ -127,6 +127,14 @@ def test_make_linear_constraints(self):
                 shapeX=torch.Size([1, 1, 2]),
                 eq=False,
             )
+        # test that len(shapeX) < 2 raises an error
+        with self.assertRaises(UnsupportedError):
+            _make_linear_constraints(
+                shapeX=torch.Size([2]),
+                indices=indices,
+                coefficients=coefficients,
+                rhs=0.0,
+            )
 
     def test_make_scipy_linear_constraints(self):
         for shapeX in [torch.Size([2, 1, 4]), torch.Size([1, 4])]: