I'm worried about race conditions w.r.t. MSW when multiple Jest test files run concurrently. Is that an issue?
The MSW getting started guide suggests the following code in setupTests.js:
// Reset any request handlers that we may add during the tests,
// so they don't affect other tests.
afterEach(() => server.resetHandlers())
But what if two tests run concurrently, and each starts with something like:
server.use(rest.get('https://api.backend.dev/user', (req, res, ctx) => {
return res(ctx.json({ firstName: 'Paul' }))
})),
or
server.use(rest.get('https://api.backend.dev/user', (req, res, ctx) => {
return res(ctx.json({ firstName: 'Ringo' }))
})),
Couldn't the handler set up in one test be called by the other test (or vice-versa)?
Do I need to use --runinband?
PS: Maybe I'm misunderstanding Jest because it seems like the "mock dom" implemented by jsdom would have the same issues with concurrently running tests.
I've at least convinced myself there's no race condition based on two facts:
Each Jest test file runs in its own subprocess. (This is mentioned in #5623 among other places.). So each test file should have its own server instance.
MSW on Node just monkey-patches functions like fetch() and XMLHttpRequest, rather than actually starting a web server. This is mentioned in #407. So, the monkey-patching should be isolated to each process running each test file.
Related
While writing integration tests in jest I would like to reproduce the same behaviour I have achieved in mocha by:
mocha -r ts-node/register tests/integration/topLevelTest.test.ts 'tests/integration/**/*.test.ts'.
topLevelTest.test.ts :
let importantVariable;
describe("should do something with my variable", () => {
importantVariable = returnSomethingImportant();
it("should important variable exists", () => {
should.exist(importantVariable)
})
})
after(() => {
importantVariable.cleanUp()
})
Behaviour was simple: firstly topLevelTest executed describe, then other test suites executed themselves, and in the end after within topLevelTest were executed.
In my attempt of rewriting it to jest I wrote something very similar. Only difference is I used afterAll instead of after. The result is: firstly topLevelTest executed describe, then afterAll, and then other test suites. Is it possible to make afterAll run after other test suites?
This is what setup files are for, more specifically setupFilesAfterEnv because Jest environment is already initialized there with globals being available.
Top-level afterAll that wasn't grouped with describe applies to all tests within current test suite. Since Jest tests run in parallel (unless runInBand option was specified) in different threads, it obviously won't affect other test suites.
In case tests need to not proceed if a setup failed and data from setup needs to not be, globalSetup and globalTeardown configuration options should be used for that. This is not a test but the main difference is that describe and separate test blocks are unavailable. Global expect is not available but can be imported, this results in meaningful errors in case a setup fails:
// setup.js
let expect = require('expect');
module.exports = async () => {
let server = ...;
expect(server)...;
global.__MYSERVER__ = server;
};
// teardown.js
module.exports = async function () {
// close __MYSERVER__
};
Since global setup and teardown run in parent process, __MYSERVER__ cannot be accessed in tests.
I'd like to run a callback when all the tests in a describe block pass (or fail), is there some hook or something in the Jest API to do this? I could not find anything applicable in the docs.
I'm making several API requests to collect data in order to compare it to data in a CSV file, in order to diff the contents. When the tests have all passed, I would like to save all the API responses in a file, therefore I need some sort of 'all tests passed' callback
You can run jest programmatically. Note that this approach is "hack" because there is no official support for running jest like this.
see: https://medium.com/web-developers-path/how-to-run-jest-programmatically-in-node-js-jest-javascript-api-492a8bc250de
There is afterAll that is aware of describe but runs regardless of test results. It can be used as a part of function to aggregate data from tests:
let responses;
testAndSaveResponses((name, fn) => {
if (!responses) {
responses = [];
} else {
afterAll(async () => {
if (!responses.includes(null)) {
// no errors, proceed with response processing
}
});
}
test(name, async () => {
try {
responses.push(await fn());
} catch (err) {
responses.push(null);
throw err;
}
});
});
It's supposed to be used instead of Jest test and be enhanced to support multiple describe scopes.
There is custom environment. Circus runner allows to hook test events, finish_describe_definition in particular. It is applied to all tests, unaware of custom data (e.g. responses that need to be saved) and should interact with them through global variables.
There is custom reporter, it receives a list of passed and failed tests. It is applied to all tests, unaware of custom data defined in tests and doesn't have access to globals from test scope so cannot be used to collect responses.
well before specifying my problem, i want to tell that i'm new to the field of testing, so here is my problem:
i developed a rest api using express + sequelize(mysql), and i want to write some test for my api. i choosed to use jasmine library for testing.
so right know i want to test the create and update rest endpoint, i will need access to a database, but the problem is that the test cases are run in parallel, and there is only one database, so if i want to delete all item from a table in a test case, and another test case have create a row in that table, there will be a problem.
const request = require('superagent');
const models = require('../../src/models');
const Station = models.Station;
describe("station testing", function () {
before(() => {
// delete and recreate all database table
// before running any test
});
describe("crud station", function () {
it('should create model', () => {
Station.create({
'name': 'test',
lat: 12,
long: 123,
}).then( model => {
expect(model).toBeTruthy();
});
});
it('should delete evrything', () => {
Station.deleteAll().then( () => {
// problem here if after the first model is created and before create model except is executed
expect(Station.Count()).toEqual(0);
}
});
});
});
Your problem is that you are not writing unit tests here.
You need to understand the most important rule of unit testing - only test one unit at a time. A unit can be thought of as an area of your code. In a traditional desktop project (Java, C#, etc), a unit would be one class. In the case of Javascript, a unit is harder to define, but it certainly will only include the Javacript. If you are including any server code (for example, the database) in your tests, then you are not unit testing, you are doing integration testing (which is also very important, but much harder).
Your Javascript will have dependencies (ie other code that it calls, say via Ajax calls), which in your case will include the server code that is called. In order to unit test, you need to make sure that you are only testing the Javascript, which means that when running the tests, you don't want the server code to be called at all. That way, you isolate any errors in that unit of code, and can be confident that any problems found are indeed in that unit. If you include other units, then it could be the other units that have the problem.
In a strongly-typed language (like Java, C#, etc), there are frameworks that allow you to set up a mock for each dependency. Whilst I haven't tried any myself (that's this week's job), there are mocking frameworks for Javascript, and you would probably need to use one of them to do real unit testing. You mock out the server code, so when you run the test, it doesn't actually hit the database at all. Apart from solving your problem, it avoids a whole load of other issues that you will likely hit at some point with your current approach.
If you don't want to use a mocking framework, one other way to do it is to change your Javascript so that the function you are testing takes an extra parameter, which is a function that does the actual server call. So, instead of...
deleteCustomer(42);
deleteCustomer(id) {
validate(id);
$.ajax(...);
}
...your code would look like this...
deleteCustomer(42, callServer);
deleteCustomer(id, serverCall) {
validate(id);
serverCall(id);
}
...where serverCall() contains the Ajax call.
Then, to unit test, you would test something like this...
deleteCustomer(42, function(){});
...so that instead of calling the server, nothing is actually done.
This is obviously going to require some rewriting of your code, which could be avoided by mocking, but would work. My advice would be to spend some time learning how to use a mocking framework. It will pay off in the long run.
Sorry this has been a bit long. Unfortunately, you're getting into a complex area of unit testing, and it's important to understand what you're doing. I strongly recommend you read up about unit testing before you go any further, as a good understanding of the basics will save you a lot of trouble later on. Anything by Robert Martin (aka Uncle Bob) on the subject will be good, but there are plenty of resources around the web.
Hope this helps. If you want any more info, or clarification, ask away.
Jasmine supports a function for beforeEach which run before each spec in a describe block.
You can use that.
describe("A spec using beforeEach and afterEach", function() {
var foo = 0;
beforeEach(function() { foo += 1; });
afterEach(function() { foo = 0; });
it("is just a function, so it can contain any code", function() {
expect(foo).toEqual(1);
});
it("can have more than one expectation", function() {
expect(foo).toEqual(1)
expect(true).toEqual(true);
});
});
So you could let the beforeEach take care of the delete operation.
Is it possible in Jest to run cleanup or teardown tasks that run after all other tests have completed? Similar to how setupFiles allows one to set up tasks after before any test has run. Bonus points if this can also run regardless if the test had any errors.
Putting afterAll(() => {}) at the top level of a file (outside any describe function) appears only to run after tests from that particular file have finished.
The use case is I have many test files that will create users in a a development database, and I don't want to make each test file responsible for cleaning up and removing the user afterwards. Errors can also happen while writing tests, so if the cleanup happens regardless of errors that would be preferable.
There's a sibling hook to setupFiles that will too fire before every test suite but right after your test runner (by default Jasmine2) has initialised global environment.
It's called setupFilesAfterEnv. Use it like this:
{
"setupFilesAfterEnv": ["<rootDir>/setup.js"]
}
Example setup.js:
beforeAll(() => console.log('beforeAll'));
afterAll(() => console.log('afterAll'));
setup.js doesn't need to export anything. It will be executed before every test suite (every test file). Because test runner is already initialised, global functions like beforeAll and afterAll are in the scope just like in your regular test file so you can call them as you like.
In jest.config.js:
module.exports = {
// ...
setupFilesAfterEnv: [
"./test/setup.js",
// can have more setup files here
],
}
In ./test/setup.js:
afterAll(() => { // or: afterAll(async () => { }); to support await calls
// Cleanup logic
});
Note:
I am using Jest 24.8
Reference:
setupFilesAfterEnv
To do some tasks after all test suites finish, use globalTeardown. Example:
In package.json:
{
"jest": {
"globalTeardown": "<rootDir>/teardownJest.js"
},
}
In teardownJest.js:
const teardown = async () => {
console.log('called after all test suites');
}
module.exports = teardown;
Keep in mind that jest imports every module from scratch for each test suit and teardown file. From official documentation:
By default, each test file gets its own independent module registry
So, you cannot share the same DB module's instance for each test suite or teardown file. Therefore, If you wanted to close db connection after all test suits, this method would not work
There looks like there is a feature called a reporter that just does exactly this:
I'm new to this and I have been searching for ways (or standards) to write proper functional tests but I still I have many unanswered questions. I'm using FrisbyJS to write functional tests for my NodeJS API application and jasmine-node to run them.
I have gone through Frisby's documentation, but it wasn't fruitful for me.
Here is a scenario:
A guest can create a User. (No username duplication allowed, obviously)
After creating a User, he can login. On successful login, he gets an Access-Token.
A User can create a Post. Then a Post can have Comment, and so on...
A User cannot be deleted once created. (Not from my NodeJS Application)
What Frisby documentation says is, I should write a test within a test.
For example (full-test.spec.js):
// Create User Test
frisby.create('Create a `User`')
.post('http://localhost/users', { ... }, {json: true})
.expectStatus(200)
.afterJSON(function (json) {
// User Login Test
frisby.create('Login `User`')
.post('http://localhost/users/login', { ... }, {json: true})
.expectStatus(200)
.afterJSON(function (json) {
// Another Test (For example, Create a post, and then comment)
})
.toss();
})
.toss();
Is this the right way to write a functional test? I don't think so... It looks dirty.
I want my tests to be modular. Separate files for each test.
If I create separate files for each test, then while writing a test for Create Post, I'll need a User's Access-Token.
To summarize, the question is: How should I write tests if things are dependent on each other?
Comment is dependent on Post. Post is dependent on User.
This is the by product to using NodeJS. This is a large reason I regret deciding on frisby. That and the fact I can't find a good way to load expected results out of a database in time to use them in the tests.
From what I understand - You basically want to execute your test cases in a sequence. One after the other.
But since this is javascript, the frisby test cases are asynchronous. Hence, to make them synchronous, the documentation suggested you to nest the test cases. Now that is probably OK for a couple of test cases. But nesting would go chaotic if there are hundreds of test cases.
Hence, we use sequenty - another nodejs module, which uses call back to execute functions(and test cases wrapped in these functions) in sequence. In the afterJSON block, after all the assertions, you have to do a call back - cb()[which is passed to your function by sequenty].
https://github.com/AndyShin/sequenty
var sequenty = require('sequenty');
function f1(cb){
frisby.create('Create a `User`')
.post('http://localhost/users', { ... }, {json: true})
.expectStatus(200)
.afterJSON(function (json) {
//Do some assertions
cb(); //call back at the end to signify you are OK to execute next test case
})
.toss();
}
function f2(cb){
// User Login Test
frisby.create('Login `User`')
.post('http://localhost/users/login', { ... }, {json: true})
.expectStatus(200)
.afterJSON(function (json) {
// Some assertions
cb();
})
.toss();
}
sequenty.run(f1,f2);