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测试环境变量

mysql.ts

const MySQLConf = {

development: {

host: 'localhost',

port: 3306,

user: 'root',

password: 'root',

database: 'local_db',

},

production: {

host: 'www.jianshu.com',

port: 3306,

user: 'root',

password: 'root',

database: 'online_db',

},

};

export default MySQLConf[process.env.NODE_ENV ?? 'development'];

mysql.spec.ts

describe('环境变量', () => {

const OLD_ENV = process.env;

beforeEach(() => {

jest.resetModules();

process.env = { ...OLD_ENV };

delete process.env.NODE_ENV;

});

it('development', () => {

process.env.NODE_ENV = 'development';

const MySQLConf = require('./mysql').default;

const expected = {

host: 'localhost',

port: 3306,

user: 'root',

password: 'root',

database: 'local_db',

};

expect(MySQLConf).toEqual(expected);

});

it('production', () => {

process.env.NODE_ENV = 'production';

const MySQLConf = require('./mysql').default;

const expected = {

host: 'www.jianshu.com',

port: 3306,

user: 'root',

password: 'root',

database: 'online_db',

};

expect(MySQLConf).toEqual(expected);

});

});

说明

每次执行一个it方法后执行(注：用 afterEach 方法也行，只是一个前后的问题)

多个测试有共享状态时，每次测试完成之后需要用 jest.resetModules() 重置模块 ，它会清空所有 required 模块的缓存，保证模块之间的隔离