def METHOD_NAME(self, ext='bam'):
    root = os.path.dirname(os.path.abspath(__file__)) + "/test_data/"
    bamFile1 = root + "testA." + ext
    bamFile2 = root + "testB." + ext
    bamFile_PE = root + "test_paired2." + ext
    chrom = '3R'
    step_size = 50
    bin_length = 50
    func_args = {'scaleFactor': 1.0}
    c = wr.WriteBedGraph(
        [bamFile1],
        binLength=bin_length,
        stepSize=step_size
    )
    return c, bamFile1, bamFile2, bamFile_PE, chrom, step_size, bin_length, func_args