fullstack react 学习笔记 unit testing(1)jest基础

使用jest

语法：

expect().toBe():相当于===，不能用于比较对象

expect().toEqual():可以用于所有值的比较，包括对象。

describe('string',()=>{

　　it('string',()=>{expect().toBe()})

})

示例：

describe('My test suite', () => {
  it('`true` should be `true`', () => {
    expect(true).toBe(true);
  });

  it('`false` should be `false`', () => {
    expect(false).toBe(false);
  });
});

　　Modash.js:

// We write the Modash library in this file in the Unit Testing chapter
function truncate(string, length) {
  if (string.length > length) {
    return string.slice(0, length) + '...';
  } else {
    return string;
  }
}

function capitalize(string) {
  return (
    string.charAt(0).toUpperCase() + string.slice(1).toLowerCase()
  );
}

function camelCase(string) {
  const words = string.split(/[\s|\-|_]+/);
  return [
    words[0].toLowerCase(),
    ...words.slice(1).map((w) => capitalize(w)),
  ].join('');
}

const Modash = {
  truncate,
  capitalize,
  camelCase,
};

export default Modash;

　　Modash.test.js

// We write the tests for the Modash library in
// this file in the Unit Testing chapter
import Modash from './Modash';

describe('Modash', () => {
  describe('`truncate()`', () => {
    const string = 'there was one catch, and that was CATCH-22';

    it('truncates a string', () => {
      expect(
        Modash.truncate(string, 19)
      ).toEqual('there was one catch...');
    });

    it('no-ops if <= length', () => {
      expect(
        Modash.truncate(string, string.length)
      ).toEqual(string);
    });
  });

  describe('capitalize()', () => {
    it('capitalizes first letter, lowercases rest', () => {
      const string = 'there was one catch, and that was CATCH-22';
      expect(
        Modash.capitalize(string)
      ).toEqual(
        'There was one catch, and that was catch-22'
      );
    });
  });

  describe('camelCase()', () => {
    it('camelizes string with spaces', () => {
      const string = 'customer responded at';
      expect(
        Modash.camelCase(string)
      ).toEqual('customerRespondedAt');
    });

    it('camelizes string with underscores', () => {
      const string = 'customer_responded_at';
      expect(
        Modash.camelCase(string)
      ).toEqual('customerRespondedAt');
    });
  });
});