def METHOD_NAME():
    A = np.random.randn(2, 3)
    B = np.random.randn(4, 5)
    Aop = NumpyMatrixOperator(A)
    Bop = NumpyMatrixOperator(B)
    Cop = BlockDiagonalOperator((Aop, Bop))
    assert Cop.source.dim == 8
    assert Cop.range.dim == 6