web前端好帮手 - Jest单元测试工具

npm install -D jest @types/jest

{
  "scripts": {
     "test": "jest",
     "test-debug": "node --inspect-brk node_modules/jest/bin/jest.js --runInBand"
  }}

const url = require("./common/url.js");

describe("url.parse", () => {
  test("解析一般url", () => {    const uri = url.parse("http://kg.qq.com/a/b.html?c=1&d=%2F");
    expect(uri.protocol).toBe("http:");
    expect(uri.hostname).toBe("kg.qq.com");    // ...
  });
  test("解析带hash的url", () => {...});
  test("解析url片段", () => {...});
});

describe("url.getParameter", () => {
  test("从指定url中获取查询参数", () => {
    expect(url.getParameter("test", "?test=hash-test")).toBe("hash-test");    // ...
  });
  test("从浏览器地址中获取查询参数", () => {...});
  test("当url中参数为空时", () => {...});
  test("必须decodeURIComponent", () => {...});
});

expect(1).toBe(1); // 测试通过expect({}).toBe({}); // 报错，因为{} !== {}

expect({}).toStrictEqual({}); // 通过expect({
  person: {
    name: "shanelv"
  }
}).toStrictEqual({
  person: {
    name: "shanelv"
  }
}); // 通过

// 假设urlParse函数对参数校验非法报错function fetchUserInfo(uid) {  if (!uid) {    throw(new Error("require uid!"));
  }  // ...}// 正确写法test('必要参数uid漏传报错', () => {
  expect(() => {
    fetchUserInfo()
  }).toThrow();
});// 错误写法test('必要参数uid漏传报错', () => {
  expect(fetchUserInfo()).toThrow();
});

const fs = require("fs");
test("测试callback读写接口", (done) => {
  fs.writeFileSync("./test.txt", "123456");
  fs.readFile("./test.txt", (err, data) => {
    expect(data.toString()).toBe("123456");
    done();
  });
});

const fs = require("fs");const util = require("util");const writeFile = util.promisify(fs.writeFile);const readFile = util.promisify(fs.readFile);

test("测试promise读写接口", async () => {
  await writeFile("./test.txt", "333");  let data = await readFile("./test.txt");
  expect(data.toString()).toBe("333");
});

function sleep(time) {  return new Promise(resolve => {
    setTimeout(resolve, time);
  });
}// 该测试会报错：Async callback was not invoked within the 1000ms timeout specified by jest.setTimeout.test("超时", async () => {
  jest.setTimeout(1000);
  await sleep(2000);
  expect(1).toBe(1);
});

function sleep(time) {  return new Promise(resolve => {
    setTimeout(resolve, time);
  });
}
test("增加Jest的超时时间", async () => {
  jest.setTimeout(3000); // <-- 修改3秒钟
  await sleep(2000);
  expect(1).toBe(1);
});

global.platform = {};function setGlobalPlatform(key, value) {
  global.platform[key] = value;
}

describe("platform", () => {  // afterEach在每个测试完成后触发回调
  afterEach(() => {
    global.platform = {};    console.log("reset platform!");
  });

  test("设置平台信息", () => {
    setGlobalPlatform("ios", true);
    expect(global.platform).toStrictEqual({
      ios: true
    });
  });

  test("设置平台信息为空值", () => {
    setGlobalPlatform("web");
    expect(global.platform).toStrictEqual({
      web: global.undefined
    });
  });
});

// 在文件全局作用域下，对该文件中所有测试用例生效afterEach(() => {...});

describe("group-A", () => {  // 在group-A作用域下，对group-A以及group-B的测试用例生效
  beforeEach(() => {})

  describe("group-B", () => {    // 在group-B作用域下，仅对group-B下测试用例生效
    beforeEach(() => {})
  });
});

expect(generateAst("./test.jce")).toMatchSnapshot("test.jce文件的AST结构");

npm run jest -- --updateSnapshot
# 或者
npm run jest -- -u

// 运行前：expect({ name: "shanelv" }).toMatchInlineSnapshot();// 运行Jest工具进行测试后，生成的行内快照：expect({ name: "shanelv" }).toMatchInlineSnapshot(`  Object {    "name": "shanelv",
  }
`)

// 运行前：expect(value).toMatchInlineSnapshot();// 运行Jest工具进行测试后，生成的行内快照：expect(value).toMatchInlineSnapshot(`  Object {    "name": "shanelv",
  }
`);// 将行内快照结果改成toStrictEqual方法！！expect(value).toStrictEqual({  "name": "shanelv",
});

// window的路径，在Mac上会报错expect(value).toMatchInlineSnapshot(`  Object {    "filePath": "f:\\code\\kg\\test.js",
  }
`);// 改成toStrictEqual时，记得把路径信息改过来expect(value).toStrictEqual({  "filePath": path.resolve(__dirname, "./test.js"),
});

test("setName方法改变name属性“, () => {
  let person = new Person({
    name: "lxj"
    job: "web"
  });
  person.setName("shanelv");

  // 不要用快照
  // expect(person).toMatchSnapshot("用户")

  // 对具体功能进行测试
  expect(person.name).toBe("shanelv")
});

npm install -D react-test-renderer

const renderer = require("react-test-renderer");
test("测试React组件渲染", () => {  let renderInstance = renderer.create(    <div>
      hello Jest    </div>
  );

  let nodeJson = renderInstance.toJSON();

  expect(nodeJson.type).toBe("div");
  expect(nodeJson.children[0]).toBe("hello Jest");
});

test("init", () => {  let store = initStore(combineReducers(reducer));  /**
   * 先处理store状态，再进行render
   */
  store.dispatch({
    type: "xxx"
  });  let renderInstance = renderer.create(    <Provider store={store}>
      <MyCom />
    </Provider>
  );

  /**
   * React渲染后,再改变store状态不会重新渲染
   */
  //store.dispatch(
  //  type: "xxx"
  //);

  let nodeJson = renderInstance.toJSON();

  // ...
});

// jest.config.jsmodule.export = { // ...
 collectCoverage: true,
};

/**
 * 以下文件已覆盖测试，改动以下代码要同时加上测试，避免测试覆盖率降低
 */let coverTestFiles = [  "library/client-side/cookie.js",  "library/client-side/url.js",  "library/h5-side/components/lazy.js",  // ...];module.export = { // ...
 collectCoverage: true, // 指定覆盖文件
 collectCoverageFrom: coverTestFiles, // 要求覆盖文件的覆盖率100%
 coverageThreshold: coverTestFiles.reduce((obj, file) => {
   obj[file] = {
     statements: 100,
     branches: 100
   };   return obj;
 }, {}),
};

/* istanbul ignore else: 跳过else分支的覆盖统计  */if (isNaN(value)) {    // ...} else {   // ...}/* istanbul ignore if: 跳过if分支的覆盖统计  */if (isNaN(value)) {    // ...}

{
  "scripts": {
     "test-debug": "node --inspect-brk node_modules/jest/bin/jest.js --runInBand"
  }}

function bigContent() {  let arr = [];  for (let i = 0; i < 1000000; i++) {
    arr.push(String(Math.random()));
  }  return arr.join(" ");
}// test-a.test.jstest("测试文件内容-A", async () => {  let content = bigContent();  // let fileName = "./test.txt"; // 危险！！
  let fileName = "./test-a.txt"; // 名称隔离
  await writeFile(fileName, content);  let data = await readFile(fileName);
  expect(data.toString()).toBe(content);
});// test-a.test.jstest("测试文件内容-B", async () => {  let content = bigContent();  // let fileName = "./test.txt"; // 危险！！
  let fileName = "./test-b.txt"; // 名称隔离
  await writeFile(fileName, content);  let data = await readFile(fileName);
  expect(data.toString()).toBe(content);
});