我正在尝试为使用Nodeunit在Node.js中编写的模块创建一个测试套件.该模块是一个基本的音乐播放列表,允许添加和删除曲目到播放列表.
var playlist = function(){
this.__playlist = [];
this.__count = 0;
};
playlist.prototype = {
addtrack:function(track){
if(typeof track !== "object") throw new Error("Track needs to be an oject");
this.__count++;
track.id = this.__count;
this.__playlist.push(track);
return this.__playlist;
},removetrack:function(trackid){
if(typeof trackid !== "number") throw new Error("Pass in a numeric track id");
var trackFound = false;
for(var i=0;i<this.__playlist.length;i++){
var t = this.__playlist[i];
if(t.id == trackid){
trackFound = true;
this.__playlist.splice(i,1);
}
}
if(!trackFound) throw new Error("Track not found in the playlist");
return this.__playlist
}
}
exports.playlist = function(){
return new playlist();
}
你可以看到有地方根据不正确的数据传入错误.
所以这里是我的测试套件.
var pl = require('./playlist');
exports.testPlaylistInit = function(test){
var playlist = pl.playlist();
test.equal(typeof playlist,'object');
test.done();
}
exports.testAddingTracks = function(test){
var playlist = pl.playlist();
test.throws(playlist.addtrack(),Error,'Should fail for blank track');
var track = {
title: "Golly Sandra",artist: "Eisley",album: "Room Noises"
};
tracks = playlist.addtrack(track);
test.equals(tracks[0],track);
test.equals(tracks[0].id,1)
test.done();
}
exports.testRemoveingTracks = function(test){
var playlist = pl.playlist();
test.throws(playlist.removetrack('Imma error'),'Show fail for non-numeric track id');
var track = {
title: "Golly Sandra",album: "Room Noises"
};
playlist.addtrack(track);
track = {
title: ".44 Calliber Love Letter",artist: "Alexisonfire",album: "Alexisonfire"
}
playlist.addtrack(track);
test.equals(playlist.removetrack(1)[0],track);
test.throws(playlist.removetrack(10),'Should fail for non-existant track');
test.done();
}
在编写测试套件时,我使用test.throws作为假设,基本上只是将代码块包装在一个try-catch语句中,并检查catch对错误块.显然我错了,因为当我使用Nodeunit运行测试时,Node会显示模块抛出的错误消息,而不是测试套件捕获错误.我使用test.throw的情况不正确吗？
解决方法
你对test.throws的使用是不正确的.如果你看看你有什么：
test.throws(
playlist.removetrack('Imma error'),'Show fail for non-numeric track id'
);
您正在执行playlist.removetrack(‘Imma error’),然后将其结果传递给throws,因此如果有异常,则会在throws被执行之前发生.
你应该做一些更像这样的事情：
test.throws(
function() {
playlist.removetrack('Imma error');
},'Show fail for non-numeric track id'
);
你必须传递一个功能,当执行时,会尝试删除轨道.这样,您的播放列表逻辑实际上由throws函数执行,因此可以自动包装在try / catch块中.
