如何使用sinon.js存根https.request response.pipe?

问题描述 投票:2回答:2

让我们说,我有这个简单的代码:

var https = require('https');
var options = {
  host: 'openshift.redhat.com',
  port: 443,
  path: '/broker/rest/api',
  method: 'GET'
};
var req = https.request(options, function(response) {
  console.log(response.statusCode);
  response.pipe(save stream to file with fs)
});
req.on('error', function(e) {
  console.error(e);
});
req.end();

好吧,我对sinon.js有点新意,我想问:如何存根response.pipe()?当然,我可以为https.request创建存根并使用.on和.end返回一些东西,这很容易,但我不知道,如何使用正确的参数调用response.pipe()...(nodejs documentation说响应是回调)在这种情况下,文档没有帮助! ofc测试环境是摩卡,也可以使用柴请给我一些建议或例子。谢谢,马特

javascript node.js unit-testing httprequest sinon
2个回答
5
投票

我将您的代码包装到一个接受回调的函数中,因为在当前实现中我们实际上并不知道管道何时实际完成。所以假设我们有这样的函数:

const downloadToFile = function (options, callback) {
	let req = https.request(options, function (err, stream) {
		let writeStream = fs.createWriteStream('./output.json');
		stream.pipe(writeStream);

		//Notify that the content was successfully writtent into a file
		stream.on('end', () => callback(null));
		//Notify the caller that error happened.
		stream.on('error', err => callback(err));
	});

	req.end();
};

有3个问题需要解决:

  1. 因为响应是可读的流。我们想模拟它发出的数据。
  2. 我们想要模拟.pipe方法检查我们是否正在向右流传输。
  3. 我们还需要模拟https.request方法,不要进行实际调用

以下是我们如何实现这一目标:

const {PassThrough} = require('stream');

describe('#downloadToFile', () => {
	it('should save the data to output.json', function (callback) {
		const mockResponse = `{"data": 123}`;
		//Using a built-in PassThrough stream to emit needed data.
		const mockStream = new PassThrough();
		mockStream.push(mockResponse);
		mockStream.end(); //Mark that we pushed all the data.

		//Patch the 'https' module not to make an actual call
		//but to return our stream instead
		sinon.stub(https, 'request', function (options, callback) {
			callback(null, mockStream);

			return {end: sinon.stub()}; //Stub end method btw
		});

		//Finally keep track of how 'pipe' is going to be called
		sinon.spy(mockStream, 'pipe');

		downloadToFile({url: 'http://google.com'}, (err) => {
			//Here you have the full control over what's happened
			sinon.assert.calledOnce(mockStream.pipe);
			//We can get the stream that we piped to.
			let writable = mockStream.pipe.getCall(0).args[0];
			assert.equal(writable.path, './output.json');

			//Tell mocha that the test is finished. Pass an error if any.
			callback(err);
		});
	});
});

稍后您可以创建单独的函数,例如:createMockedStream。或者甚至将所有这些准备工作提取到一个单独的方法中,并在测试中仅保留断言。


1
投票

从Sinon文档中,这已从v3.0.0中删除:

var stub = sinon.stub(object, "method", func);`

相反,你应该使用:

stub(obj, 'meth').callsFake(fn)
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