执行多个摩卡测试

Question

如果我有一组URL来访问：

let tests = [ 
    { status: 200, mediaType: 'text/html', req: { method: 'GET', uri: 'http://stackoverflow.com/' } }, 
    { status: 200, mediaType: 'text/html', req: { method: 'GET', uri: 'http://stackoverflow.com999/' } }, 
    { status: 200, mediaType: 'text/html', req: { method: 'GET999', uri: 'http://stackoverflow.com/' } }, 
] 

和一组测试对每个执行：

it('should have status ' + test.status,() => { 
    expect(test.response.statusCode).to.equal(test.status) 
}) 
it('should have content type ' + test.mediaType,() => { 
    let s = test.response.headers['content-type'] 
    let mediaType = s.indexOf(';') === -1 ? s : s.substr(0, s.indexOf(';')) 
    expect(mediaType).to.equal(test.mediaType) 
}) 
it('should have a body',() => { 
    expect(test.body).to.not.equal('') 
}) 

我怎样才能在每套测试中只执行一次昂贵的操作？另外，如果URL不加载，我不想运行测试。

Answer 1

mocha Working With Promises documentation有一个例子，其中每个测试都等待一个beforeEach承诺在执行之前完成。如果你需要一个beforeEach反正，你可以保存为beforeEach这个承诺，你可以让他们都等待一个承诺：

let P = null 
beforeEach(function() { 
    if (!P) P = new Promise(...) 
    return P 
}) 

但更可能的是，你只需要使用一个before：

beforeEach(function() { 
    return new Promise(...) 
}) 

对于这个问题的完整列表：

let expect = require('chai').expect 
let request = require('request') 

let tests = [ 
    { status: 200, mediaType: 'text/html', req: { method: 'GET', uri: 'http://localhost/' } }, 
    { status: 200, mediaType: 'text/html', req: { method: 'GET', uri: 'http://localhost999/' } }, 
    { status: 200, mediaType: 'text/html', req: { method: 'GET999', uri: 'http://localhost/' } }, 
] 

tests.forEach(function (test) { 
    describe(test.req.method + ' ' + test.req.uri, function() { 
    before('should load', function() { 
     return new Promise(function (resolve, reject) { 
     request(test.req, function (error, response, body) { 
      if (error) { 
      reject(test.rejection = error) 
      } else { 
      test.response = response 
      test.body = response 
      resolve() 
      } 
     }) 
     }) 
    }); 

    it('should have status ' + test.status,() => { 
     expect(test.response.statusCode).to.equal(test.status) 
    }) 
    it('should have content type ' + test.mediaType,() => { 
     let s = test.response.headers['content-type'] 
     let mediaType = s.indexOf(';') === -1 ? s : s.substr(0, s.indexOf(';')) 
     expect(mediaType).to.equal(test.mediaType) 
    }) 
    it('should have a body',() => { 
     expect(test.body).to.not.equal('') 
    }) 
    }) 
}) 

这给了你漂亮流利的输出：

GET http://stackoverflow.com/ 
    ✓ should have status 200 
    ✓ should have content type text/html 
    ✓ should have a body 

    GET http://stackoverflow.com999/ 
    1) "before each" hook: should load for "should have status 200" 

    GET999 http://stackoverflow.com/ 
    ✓ should have status 200 
    ✓ should have content type text/html 
    ✓ should have a body 

如果你改变的例子使用计算器的本地主机这一翻译，你可以看访问日志，以验证每个URL被加载一次：

127.0.0.1 - - [21/Oct/2017:06:52:10 -0400] "GET/HTTP/1.1" 200 12482 "-" "-" 
127.0.0.1 - - [21/Oct/2017:06:52:10 -0400] "GET999/HTTP/1.1" 501 485 "-" "-" 

注意，最后的操作，GET999 http://stackoverflow.com/给出了一个200在stackoverflow上（通过清漆缓存）和apache上的501：

2) GET999 http://localhost/ 
     should have status 200: 

     AssertionError: expected 501 to equal 200 
     + expected - actual 

     -501 
     +200