chai 测试：包含对象类型的数组

Question

我目前正在测试一个 Node.js/Typescript 应用程序。

我的函数应该返回一个对象数组。

这些对象的类型应该是：

type myType = {
  title: string;
  description: string;
  level: number;
  categorie: string;
  name: string;
};

以下代码不起作用

const ach: any = await achievementsServiceFunctions.getAchievementsDeblocked(idAdmin);
expect(ach)
  .to.be.an('array')
  .that.contains('myType');

如何检查我的数组是否只包含给定的类型？ （在 chai doc 上没有找到此信息）

Answer 1

Chai 没有提供直接的方法来测试数组的所有元素的类型。所以假设数组的所有元素都是相同的类型，我首先测试目标确实是一个数组，然后遍历它的内容来测试它们的类型，如下所示：

const expect = require('chai').expect

// create a new type 
class MyType extends Object {
  constructor() {
    super()
  }
}
// Note that this should be consistent with 
// TypeScript's 'type' directive)

// create some testable data
const ary = [
  new MyType,
  'this will FAIL',
  new MyType
]

// first, test for array type
expect(ary).to.be.an('array')

// then, iterate over the array contents and test each for type
ary.forEach((elt, index) => {
    expect(
      elt instanceof MyType, 
      `ary[${index}] is not a MyType`
    ).to.be.true
})

将输出：

/.../node_modules/chai/lib/chai/assertion.js:141
  throw new AssertionError(msg, {
  ^
AssertionError: ary[1] is not a MyType: expected false to be true
  at ary.forEach (.../testElementTypes.js:12:38)
  at Array.forEach (<anonymous>)
  at Object.<anonymous> (.../testElementTypes.js:11:5)
  at Module._compile (module.js:624:30)
  at Object.Module._extensions..js (module.js:635:10)
  at Module.load (module.js:545:32)
  at tryModuleLoad (module.js:508:12)
  at Function.Module._load (module.js:500:3)
  at Function.Module.runMain (module.js:665:10)
  at startup (bootstrap_node.js:187:16)

如果数组内容不是同质的，您需要分别测试每个元素的类型。

Answer 2

您也可以使用chai-json-pattern 插件来做到这一点。

Chai JSON 模式允许您为 JavaScript 对象创建蓝图，以确保验证关键信息。它使您能够使用带有易于使用的验证器的 JSON 语法扩展。

另外，由于chai-json-pattern插件目前不支持TypeScript，我们需要扩展chai.Assertion的方法类型。

我使用faker包生成符合myType的随机测试数据。

例如

import faker from 'faker';
import chai, { expect } from 'chai';
import chaiJsonPattern from 'chai-json-pattern';
chai.use(chaiJsonPattern);

declare global {
  export namespace Chai {
    interface Assertion {
      matchPattern(pattern: string): void;
    }
  }
}

type myType = {
  title: string;
  description: string;
  level: number;
  categorie: string;
  name: string;
};

describe('49047322', () => {
  it('should pass if the data has correct types', () => {
    const ach: myType[] = [
      {
        title: faker.name.title(),
        description: faker.lorem.sentence(),
        level: faker.random.number(),
        categorie: faker.lorem.word(),
        name: faker.name.findName(),
      },
      {
        title: faker.name.title(),
        description: faker.lorem.sentence(),
        level: faker.random.number(),
        categorie: faker.lorem.word(),
        name: faker.name.findName(),
      },
    ];
    expect(ach).to.matchPattern(`
      [
       {
        "title": String,
        "description":String,
        "level": Number,
        "categorie": String,
        "name": String
       }
      ]
    `);
  });

  it('should fail if the data has incorrect types', () => {
    const ach: myType[] = [
      {
        title: 1 as any,  // Simulate wrong type of data
        description: faker.lorem.sentence(),
        level: faker.random.number(),
        categorie: faker.lorem.word(),
        name: faker.name.findName(),
      },
    ];
    expect(ach).to.matchPattern(`
      [
       {
        "title": String,
        "description":String,
        "level": Number,
        "categorie": String,
        "name": String
       }
      ]
    `);
  });
});

测试结果：

  49047322
    ✓ should pass if the data has correct types
    1) should fail if the data has incorrect types


  1 passing (27ms)
  1 failing

  1) 49047322
       should fail if the data has incorrect types:

      AssertionError: expected [ Array(1) ] to be like [ Array(1) ]
      + expected - actual

           "categorie": "nisi"
           "description": "Quae aut sint et earum quae."
           "level": 69341
           "name": "Mozell Green MD"
      -    "title": 1
      +    "title": "String"
         }
       ]
      
      at Context.it (src/stackoverflow/49047322/main.test.ts:63:20)