[tests] Fix test__boundaries.py
@@ -47,4 +47,4 @@ class TestFieldMath(TestCase):
grid = CenteredGrid(1, a=4, b=3)
self.assertEqual(spatial(a=4, b=3), grid.shape)
grid = StaggeredGrid(1, a=4, b=3)
- self.assertEqual(spatial(a=4, b=3) & channel(vector=2), grid.shape)
+ self.assertEqual(spatial(a=4, b=3) & channel(vector='a,b'), grid.shape)
