Joi object schema:

import Joi from 'joi';

export const schema = Joi.object({
  payway: Joi.when('productPackageType', {
    is: Joi.string().valid('1', '6', '7'),
    then: Joi.array().min(1).max(2).items(Joi.string().valid('alipay', 'wxpay').required())
      .required()
      .messages({
        'array.min': 'payway is required',
        'array.includesRequiredUnknowns': 'payway is not correct',
      }),
    otherwise: Joi.optional(),
  }),
  productPackageType: Joi.string().required(),
});

test file:

test.only('should validate error if productPackageType is "1" and payway is an empty array ', () => {
  const v = {
    payway: [],
    productPackageType: '1',
  };
  const r = schema.validate(v);
  expect(r.error?.details[0].message).toMatch('payway is required');
});

Test failed:

● validator › schema › should validate error if productPackageType is "1" and payway is an empty array 

    expect(received).toMatch(expected)

    Expected substring: "payway is required"
    Received string:    "payway is not correct"

      22 |       };
      23 |       const r = schema.validate(v);
    > 24 |       expect(r.error?.details[0].message).toMatch('payway is required');
         |                                           ^
      25 |     });
      26 |
      27 |     //   test('should validate error if productPackageType is "1" and payway has invalid element', () => {

I expect Joi should validate the array length firstly then the element in the array. This means the error message should be 'payway is required' rather than 'payway is not correct'.

I don't know what is the priority of the Joi validation. Which validator is used firstly, .min(1) or .items(Joi.string().valid('alipay', 'wxpay').required())?