Mocking specific reading file error for tests in Node.js
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.
node.js unit-testing mocking fs
asked Nov 16 '18 at 8:07
SergeySergey
1,3361425
add a comment |
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.
node.js unit-testing mocking fs
asked Nov 16 '18 at 8:07
SergeySergey
1,3361425
add a comment |
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.
node.js unit-testing mocking fs
asked Nov 16 '18 at 8:07
SergeySergey
1,3361425
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.
node.js unit-testing mocking fs
node.js unit-testing mocking fs
asked Nov 16 '18 at 8:07
SergeySergey
1,3361425
asked Nov 16 '18 at 8:07
SergeySergey
1,3361425
asked Nov 16 '18 at 8:07
SergeySergey
1,3361425
asked Nov 16 '18 at 8:07
SergeySergey
1,3361425
asked Nov 16 '18 at 8:07
SergeySergey
1,3361425
1,3361425
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
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:
proxyquire (see example below)- testdouble
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
answered Nov 16 '18 at 11:19
lependulependu
724314
ReadingFileErroris a custom class that inherits fromError.
– Sergey
Nov 16 '18 at 11:30
That is what I assumed (see note), but I don't have it, so I can't use it in the example. It does not change anything :)
– lependu
Nov 16 '18 at 11:31
add a comment |
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53333758%2fmocking-specific-reading-file-error-for-tests-in-node-js%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
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:
proxyquire (see example below)- testdouble
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
answered Nov 16 '18 at 11:19
lependulependu
724314
ReadingFileErroris a custom class that inherits fromError.
– Sergey
Nov 16 '18 at 11:30
That is what I assumed (see note), but I don't have it, so I can't use it in the example. It does not change anything :)
– lependu
Nov 16 '18 at 11:31
add a comment |
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:
proxyquire (see example below)- testdouble
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
answered Nov 16 '18 at 11:19
lependulependu
724314
ReadingFileErroris a custom class that inherits fromError.
– Sergey
Nov 16 '18 at 11:30
That is what I assumed (see note), but I don't have it, so I can't use it in the example. It does not change anything :)
– lependu
Nov 16 '18 at 11:31
add a comment |
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:
proxyquire (see example below)- testdouble
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
answered Nov 16 '18 at 11:19
lependulependu
724314
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:
proxyquire (see example below)- testdouble
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
answered Nov 16 '18 at 11:19
lependulependu
724314
edited Nov 16 '18 at 19:04
answered Nov 16 '18 at 11:19
lependulependu
724314
answered Nov 16 '18 at 11:19
lependulependu
724314
answered Nov 16 '18 at 11:19
lependulependu
724314
724314
ReadingFileErroris a custom class that inherits fromError.
– Sergey
Nov 16 '18 at 11:30
That is what I assumed (see note), but I don't have it, so I can't use it in the example. It does not change anything :)
– lependu
Nov 16 '18 at 11:31
add a comment |
ReadingFileErroris a custom class that inherits fromError.
– Sergey
Nov 16 '18 at 11:30
That is what I assumed (see note), but I don't have it, so I can't use it in the example. It does not change anything :)
– lependu
Nov 16 '18 at 11:31
ReadingFileError is a custom class that inherits from Error.– Sergey
Nov 16 '18 at 11:30
ReadingFileError is a custom class that inherits from Error.– Sergey
Nov 16 '18 at 11:30
That is what I assumed (see note), but I don't have it, so I can't use it in the example. It does not change anything :)
– lependu
Nov 16 '18 at 11:31
That is what I assumed (see note), but I don't have it, so I can't use it in the example. It does not change anything :)
– lependu
Nov 16 '18 at 11:31
add a comment |
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53333758%2fmocking-specific-reading-file-error-for-tests-in-node-js%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
