code: def test_validation_in_config(self, app, client):
      app.config["RESTPLUS_VALIDATE"] = True
      api = restplus.Api(app)
  
      fields = api.model(
          "Person",
          {
              "name": restplus.fields.String(required=True),
              "age": restplus.fields.Integer,
              "birthdate": restplus.fields.DateTime,
          },
      )
  
      @api.route("/validation/")
      class ValidationOn(restplus.Resource):
          @api.expect(fields)
          def post(self):
              return {}
  
      self.assert_errors(client, "/validation/", {}, "name")
  
imports: from __future__ import unicode_literals
  import flask_restplus
label_desc: Use image node_id 10 for calling the PayloadTest obj's underlying member method code with example usage: obj.test_validation_in_config(app, client) and returns: dict