def METHOD_NAME(IOtest_mtz):
    """Test roundtrip of rs.read_mtz() and DataSet.write_mtz() with merged MTZ file"""
    expected = rs.read_mtz(IOtest_mtz)
    temp1 = tempfile.NamedTemporaryFile(suffix=".mtz")
    temp2 = tempfile.NamedTemporaryFile(suffix=".mtz")
    expected.write_mtz(temp1.name)
    result = rs.read_mtz(temp1.name)
    result.write_mtz(temp2.name)
    assert_frame_equal(result, expected)
    assert filecmp.cmp(temp1.name, temp2.name)
    # Clean up
    temp1.close()
    temp2.close()