Chai Custom Matchers (TypeScript)

each.matcher.ts

/**
 * @file Custom Matchers - each
 * @module tests/config/matchers/each
 */

/**
 * Wraps each item in an array in a {@link chai.Assertion}.
 *
 * [1]: https://www.chaijs.com/api
 * [2]: https://www.chaijs.com/api/plugins
 *
 * @param {Chai.ChaiStatic} chai - [`chai`][1] module
 * @param {Chai.ChaiUtils} utils - [Plugin utilities][2]
 * @return {void} Nothing when complete
 */
const each = (chai: Chai.ChaiStatic, utils: Chai.ChaiUtils): void => {
  return utils.addMethod(
    chai.Assertion.prototype,
    each.name,
    function (
      this: Chai.Assertion,
      fn: (item: Chai.Assertion, index: number) => any
    ): Chai.Assertion {
      const array: any[] = utils.flag(this, 'object')

      for (const [index, target] of array.entries()) {
        fn(new chai.Assertion(target), index)
      }

      return this
    }
  )
}

export default each

global.d.ts

// typings/chai/global.d.ts

declare module 'chai' {
  import type { ExceptionCode } from '@flex-development/exceptions/enums'
  import type { HttpStatus } from '@nestjs/common'

  global {
    export namespace Chai {
      interface Assertion {
        each(fn: (item: Chai.Assertion, index: number) => any): Chai.Assertion
        jsonResponse(
          status?: HttpStatus | ExceptionCode,
          body?: 'array' | 'object'
        ): Chai.Assertion
      }
    }
  }
}

json-response.matcher.ts

import { ExceptionCode } from '@flex-development/exceptions/enums'
import { HttpStatus } from '@nestjs/common'
import type { Response } from 'superagent'

/**
 * @file Custom Matchers - jsonResponse
 * @module tests/config/jsonResponse
 */

/**
 * Checks if a {@link Response} contains JSON content.
 *
 * The {@link Response#body} type and {@link Response#status} can be verified as
 * well. Response bodies are expected to be an array or object.
 *
 * [1]: https://www.chaijs.com/api
 * [2]: https://www.chaijs.com/api/plugins
 *
 * @see https://github.com/visionmedia/superagent
 * @see https://github.com/chaijs/chai-http#assertions
 *
 * @param {Chai.ChaiStatic} chai - [`chai`][1] module
 * @param {Chai.ChaiUtils} utils - [Plugin utilities][2]
 * @return {void} Nothing when complete
 */
const jsonResponse = (chai: Chai.ChaiStatic, utils: Chai.ChaiUtils): void => {
  return utils.addMethod(
    chai.Assertion.prototype,
    jsonResponse.name,
    function (
      this: Chai.Assertion,
      estatus: HttpStatus | ExceptionCode = HttpStatus.OK,
      ebody?: 'array' | 'object'
    ): Chai.Assertion {
      const res: Response = utils.flag(this, 'object')
      const message_body = `expected response body to be an ${ebody}`

      new chai.Assertion(res).to.have.status(estatus)
      new chai.Assertion(res).to.be.json
      ebody && new chai.Assertion(res.body).to.be.an(ebody, message_body)

      return this
    }
  )
}

export default jsonResponse