我在测试自己的路由处理程序时没有遇到任何问题,但在这种情况下,我想测试 express 的静态处理程序。我终其一生都无法弄清楚它为什么会挂起。显然,我缺少一些回调或需要发出一些事件。
我尽量做最小的例子。
var events = require('events');
var express = require('express');
var stream = require('stream');
var util = require('util');
function MockResponse(callback) {
stream.Writable.call(this);
this.headers = {};
this.statusCode = -1;
this.body = undefined;
this.setHeader = function(key, value) {
this.headers[key] = value;
}.bind(this);
this.on('finish', function() {
console.log("finished response");
callback();
});
};
util.inherits(MockResponse, stream.Writable);
MockResponse.prototype._write = function(chunk, encoding, done) {
if (this.body === undefined) {
this.body = "";
}
this.body += chunk.toString(encoding !== 'buffer' ? encoding : undefined);
done();
};
function createRequest(req) {
var emitter = new events.EventEmitter();
req.on = emitter.on.bind(emitter);
req.once = emitter.once.bind(emitter);
req.addListener = emitter.addListener.bind(emitter);
req.emit = emitter.emit.bind(emitter);
return req;
};
describe('test', function() {
var app;
before(function() {
app = express();
app.use(express.static(__dirname));
});
it('gets test.js', function(done) {
var req = createRequest({
url: "http://foo.com/test.js",
method: 'GET',
headers: {
},
});
var res = new MockResponse(responseDone);
app(req, res);
function responseDone() {
console.log("done");
done();
}
});
});
设置,
mkdir foo
cd foo
mkdir test
cat > test/test.js # copy and paste code above
^D
npm install express
npm install mocha
node node_modules/mocha/bin/mocha --recursive
它只是超时。
我错过了什么?
我还尝试将请求设为可读流。没有变化
var events = require('events');
var express = require('express');
var stream = require('stream');
var util = require('util');
function MockResponse(callback) {
stream.Writable.call(this);
this.headers = {};
this.statusCode = -1;
this.body = undefined;
this.setHeader = function(key, value) {
this.headers[key] = value;
}.bind(this);
this.on('finish', function() {
console.log("finished response");
callback();
});
};
util.inherits(MockResponse, stream.Writable);
MockResponse.prototype._write = function(chunk, encoding, done) {
if (this.body === undefined) {
this.body = "";
}
this.body += chunk.toString(encoding !== 'buffer' ? encoding : undefined);
done();
};
function MockMessage(req) {
stream.Readable.call(this);
var self = this;
Object.keys(req).forEach(function(key) {
self[key] = req[key];
});
}
util.inherits(MockMessage, stream.Readable);
MockMessage.prototype._read = function() {
this.push(null);
};
describe('test', function() {
var app;
before(function() {
app = express();
app.use(express.static(__dirname));
});
it('gets test.js', function(done) {
var req = new MockMessage({
url: "http://foo.com/test.js",
method: 'GET',
headers: {
},
});
var res = new MockResponse(responseDone);
app(req, res);
function responseDone() {
console.log("done");
done();
}
});
});
我还在挖掘。查看静态服务器内部,我看到它通过调用 fs.createReadStream
创建了一个可读流。它确实有效
var s = fs.createReadStream(filename);
s.pipe(res);
所以试着让我自己工作就好了
it('test stream', function(done) {
var s = fs.createReadStream(__dirname + "/test.js");
var res = new MockResponse(responseDone);
s.pipe(res);
function responseDone() {
console.log("done");
done();
}
});
我认为这可能与快速等待输入流完成有关,但似乎也不是这样。如果我使用带有响应的模拟输入流,它就可以正常工作
it('test msg->res', function(done) {
var req = new MockMessage({});
var res = new MockResponse(responseDone);
req.pipe(res);
function responseDone() {
console.log("done");
done();
}
});
任何我可能缺少的见解都会有所帮助
注意:虽然对第 3 方模拟库的建议表示赞赏,但我仍然非常想了解自己缺少什么。即使我最终切换到某个库,我仍然想知道为什么这不起作用。
最佳答案
我发现了两个导致 finish
回调无法执行的问题。
serve-static
使用send
模块,该模块用于从路径创建文件读取流并将其通过管道传输到res
对象。但是该模块使用on-finished
模块检查响应对象中的finished
属性是否设置为 false,否则 destroys the file readstream .所以文件流永远没有机会发出数据事件。express initialization覆盖响应对象原型(prototype)。所以像
end()
这样的默认流方法被 http 响应原型(prototype)覆盖:exports.init = function(app){ return function expressInit(req, res, next){ ... res.__proto__ = app.response; .. }; };
为了防止这种情况,我在静态中间件之前添加了另一个中间件,以将其重置回
MockResponse
原型(prototype):app.use(function(req, res, next){ res.__proto__ = MockResponse.prototype; //change it back to MockResponse prototype next(); });
以下是使其与 MockResponse
一起使用所做的更改:
...
function MockResponse(callback) {
...
this.finished = false; // so `on-finished` module doesn't emit finish event prematurely
//required because of 'send' module
this.getHeader = function(key) {
return this.headers[key];
}.bind(this);
...
};
...
describe('test', function() {
var app;
before(function() {
app = express();
//another middleware to reset the res object
app.use(function(req, res, next){
res.__proto__ = MockResponse.prototype;
next();
});
app.use(express.static(__dirname));
});
...
});
编辑:
正如@gman 所指出的,可以使用直接属性而不是原型(prototype)方法。在这种情况下,不需要额外的中间件来覆盖原型(prototype):
function MockResponse(callback) {
...
this.finished = false; // so `on-finished` module doesn't emit finish event prematurely
//required because of 'send' module
this.getHeader = function(key) {
return this.headers[key];
}.bind(this);
...
//using direct property for _write, write, end - since all these are changed when prototype is changed
this._write = function(chunk, encoding, done) {
if (this.body === undefined) {
this.body = "";
}
this.body += chunk.toString(encoding !== 'buffer' ? encoding : undefined);
done();
};
this.write = stream.Writable.prototype.write;
this.end = stream.Writable.prototype.end;
};
关于javascript - 如何为 express.static 模拟 http.ServerResponse 和 http.IncomingMessage,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/32598066/