def METHOD_NAME(self):
    instance = self.env["mis.report.instance"].create(
        dict(name="test instance", report_id=self.report.id, comparison_mode=True)
    )
    self.pbud1 = self.env["mis.report.instance.period"].create(
        dict(
            name="pbud1",
            report_instance_id=instance.id,
            source=SRC_MIS_BUDGET_BY_ACCOUNT,
            source_mis_budget_by_account_id=self.budget.id,
            manual_date_from="2017-01-01",
            manual_date_to="2017-01-31",
        )
    )
    matrix = instance._compute_matrix()
    assert_matrix(matrix, [[24]])