'Test rendering of the hidden data element'

def testRender(self):

    widget = S3FilterWidget(['name', 'organisation_id$name'])
    widget.widget = (lambda resource, values: '')
    resource = current.s3db.resource('org_office')
    output = widget(resource, get_vars={})
    self.assertTrue(isinstance(output[0], INPUT))
    attr = output[0].attributes
    t = attr['_type']
    self.assertEqual(t, 'hidden')
    c = attr['_class']
    self.assertTrue(('filter-widget-data' in c))
    self.assertTrue((('%s-data' % widget._class) in c))
    i = attr['_id']
    self.assertEqual(i, ('%s-org_office_name-org_organisation_name-%s-data' % (resource.alias, widget._class)))
    v = attr['_value']
    self.assertEqual(v, '~.name|~.organisation_id$name')
