def METHOD_NAME(self):
    # empty
    g = GroupCoordinates([])
    # same dims, unstacked
    c1 = Coordinates([[0, 1], [0, 1]], dims=["lat", "lon"])
    c2 = Coordinates([[10, 11], [10, 11]], dims=["lat", "lon"])
    g = GroupCoordinates([c1, c2])
    # same dims, stacked
    c2 = Coordinates([[[0, 1], [0, 1]]], dims=["lat_lon"])
    c2 = Coordinates([[[10, 11], [10, 11]]], dims=["lat_lon"])
    g = GroupCoordinates([c1, c2])
    # different order
    c1 = Coordinates([[0, 1], [0, 1]], dims=["lat", "lon"])
    c2 = Coordinates([[10, 11], [10, 11]], dims=["lon", "lat"])
    g = GroupCoordinates([c1, c2])
    # different stacking
    c1 = Coordinates([[0, 1], [0, 1]], dims=["lat", "lon"])
    c2 = Coordinates([[[10, 11], [10, 11]]], dims=["lat_lon"])
    g = GroupCoordinates([c1, c2])