[英]How would I go about unit testing something with file streams in node.js?
我的源代码是:
var _ = require('lodash');
var fs = require('fs');
var csv = require('fast-csv');
var topPostStream = fs.createWriteStream('top_posts.csv');
var topOtherStream = fs.createWriteStream('other_posts.csv');
var topCsvStream = csv.createWriteStream();
var otherCsvStream = csv.createWriteStream();
var dailyTops = {};
var headerRow = [];
topCsvStream.pipe(topPostStream);
otherCsvStream.pipe(topOtherStream);
console.log(process.argv);
csv
.fromPath('posts.csv')
.on('data', function(rowData) {
if(headerRow.length === 0) {
// Save header row in CSV's
headerRow = rowData;
topCsvStream.write(headerRow);
otherCsvStream.write(headerRow);
return;
}
if(rowData[2] === 'public' && rowData[5] > 10 && rowData[4] > 9000 && rowData[1].length < 40) {
// Save to the top_posts file
topCsvStream.write(rowData);
} else {
// Save to the other_posts file
otherCsvStream.write(rowData);
}
// Save to the daily tops
var postDate = new Date(rowData[6]);
postDate = new Date(postDate.getYear(), postDate.getMonth(), postDate.getDate());
if(!dailyTops[postDate] || parseInt(rowData[3]) > parseInt(dailyTops[postDate][3])) {
dailyTops[postDate] = rowData;
}
})
.on('end', finishWrite);
function finishWrite() {
topCsvStream.end();
otherCsvStream.end();
writeDailyList(dailyTops, headerRow);
}
function writeDailyList(dailyTops, headerRow) {
var daily = _.map(_.keys(dailyTops), function(key) {
return dailyTops[key];
});
var daily = [headerRow].concat(daily);
csv
.writeToPath('daily_top_posts.csv', daily, {headers: true})
}
我需要编写单元测试来获得接近100%的覆盖率。 我的问题是(a)测试似乎太简单了;(b)我将如何实际测试单元测试?
发布我的评论作为扩展答案。
首先,您需要将数据句柄函数提取到另一个模块中,例如data-handler.js
(这是您的代码的示例,可以对其进行增强以使其看起来更好,但只是给出了一个主意)
module.exports = {
handler: (rowData, topCsvStream, otherCsvStream) => {
if(headerRow.length === 0) {
// Save header row in CSV's
headerRow = rowData;
topCsvStream.write(headerRow);
otherCsvStream.write(headerRow);
return;
}
if(rowData[2] === 'public' && rowData[5] > 10 && rowData[4] > 9000 && rowData[1].length < 40) {
// Save to the top_posts file
topCsvStream.write(rowData);
} else {
// Save to the other_posts file
otherCsvStream.write(rowData);
}
// Save to the daily tops
var postDate = new Date(rowData[6]);
postDate = new Date(postDate.getYear(), postDate.getMonth(), postDate.getDate());
if(!dailyTops[postDate] || parseInt(rowData[3]) > parseInt(dailyTops[postDate][3])) {
dailyTops[postDate] = rowData;
}
},
end: (topCsvStream, otherCsvStream) => {
topCsvStream.end();
otherCsvStream.end();
writeDailyList(dailyTops, headerRow);
}
}
在主文件中,您将引用模块:
const handler = require("./data-handler");
csv
.fromPath('posts.csv')
.on("data", (data) => handler.handler(data, topCsvStream, otherCsvStream).on("end", () => handler.end(topCsvStream, otherCsvStream));
现在,您的处理程序代码不再绑定到流,并且无需它们就可以轻松对其进行测试。
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