properly use the new vectorized_indexers strategy

Author: keewis

xarray_array_testing/indexing.py

@@ -69,7 +69,7 @@ def test_variable_isel_orthogonal(self, data):
     @given(st.data())
     def test_variable_isel_vectorized(self, data):
         variable = data.draw(xrst.variables(array_strategy_fn=self.array_strategy_fn))
-        idx = data.draw(vectorized_indexers(variable.sizes))
+        idx = data.draw(vectorized_indexers(sizes=variable.sizes, min_dims=1))
 
         with self.expected_errors("isel_vectorized", variable=variable):
             actual = variable.isel(idx).data