Not all fields of TestTaxViewResult get computed by TestTax Wizard
The field base_code, base_sign, tax_code and tax_sign are not computed by the wizard. I think it happend with this changeset[1].
For me it is not clear what needs to be fixed. Either the missing values must be computed or the fields must be removed from the view.
[1] http://hg.tryton.org/modules/account/rev/9135d0ac6abd