Is it possible to mock, let's say, with the "mock-fs" library some sort of reading file errors? In particular, I want to test this case (where code !== 'ENOENT'):
fs.readFile(filePath, (err, data) => {
if (err) {
if (err.code !== 'ENOENT') {
return done(new ReadingFileError(filePath));
}
}
// ...
});
I could find nothing about emulating reading errors in their docs. Maybe there are some other libraries that can do this.
As far as I know mock-fs mocks the filesystem not the node utility. Of course in some case you can use that to test the fs utility, but I think your use case is not amongs them.
Here is an example with sinon.sandbox
Some alternatives are:
Note, that I am a bit confused where the
ReadingFileErrorcomes from, so I guess you are trying to implement a custom error. If that is the case maybe this also will be helpful. In the example I replaced that with a simplenew Error('My !ENOENT error').
// readfile.js
'use strict'
const fs = require('fs')
function myReadUtil (filePath, done) {
fs.readFile(filePath, (err, data) => {
if (err) {
if (err.code !== 'ENOENT') {
return done(err, null)
}
return done(new Error('My ENOENT error'), null)
}
return done(null, data)
})
}
module.exports = myReadUtil
// test.js
'use strict'
const assert = require('assert')
const proxyquire = require('proxyquire')
const fsMock = {
readFile: function (path, cb) {
cb(new Error('My !ENOENT error'), null)
}
}
const myReadUtil = proxyquire('./readfile', { 'fs': fsMock })
myReadUtil('/file-throws', (err, file) => {
assert.equal(err.message, 'My !ENOENT error')
assert.equal(file, null)
})
Edit: Refactored the example to use node style callback instead of throw and try/catch
