atlas-cleanup-tests
v1.0.2
Published
Seamlessly wrap sync mocha tests with your cleanup script. Supports 'done' callback.
Downloads
4
Maintainers
Readme
atlas-cleanup-tests
Seamlessly wrap sync mocha tests with your cleanup script. Supports 'done' callback.
install
npm install --save-dev atlas-cleanup-tests
why
If you are mocking an API in a mocha test, you may need to revert changes after the test is done. The afterEach
hook in mocha runs after mocha tries to output the results for the test. This means that if your test mocks an API that mocha depends on (e.g. process.stdout
), mocha itself will fail.
If we try and mock console.log
, mocha will break:
// Animal.test.js
const mocha = require("mocha");
const { expect } = require("chai");
const rewire = require("rewire")
const Animal = rewire("./Animal")
// a handle for reverting mocks
let revert;
describe("cat", function(){
afterEach(function(){
// this code doesn't get called soon enough
revert()
})
it("should meow", function(){
let sound;
// this mocks 'console.log' for our Animal module
revert = Animal.__set__("console.log", msg => {sound = msg})
const cat = new Animal();
cat.roar();
expect(sound).to.equal("meow!")
})
})
Fixing this isn't too difficult to do inside your tests, but I like to keep a clean house. Additionally, mocking standard output is pretty avoidable. By using a wrapper (e.g. a Logger) around console.log
or process.stdout
, you can easily mock your application's logging functionality. For simple stuff though, using a special logger feels uneccesary.
This package gives you a cleanup function which runs after your test runs, but before afterEach
runs. This way, your home stays clean before mocha gets invited over.
examples
without done
callback
// Animal.test.js
...
const Cleaner = require("atlas-cleanup-tests");
const cleanup = Cleaner(() => {
revert()
console.log("cleanup script done!")
})
// seamlessly wrap your tests
describe("cat", function(){
it("should meow", cleanup(function(){
let sound;
revert = Animal.__set__("console.log", msg => {sound = msg})
const cat = new Animal();
cat.roar();
expect(sound).to.equal("meow!")
}))
})
with done
callback
Even if your test is sync, mocha's done
callback can be used to test (partial) code-paths. The cleanup
function will also be able to wrap these tests without any work on your part:
// Animal.test.js
...
describe("cat", function(){
it("should lose health when it roars", cleanup(function(done){
let sound;
revert = Animal.__set__("console.log", msg => {
expect(msg).to.equal("meow!");
// don't care about anything verifying meow
done();
})
const cat = new Animal();
cat.roar();
}))
})
caveats
This wrapper assumes that you have mocked your async dependencies. It will not catch unhandled async errors (e.g. assertions made in an async callback). Unless you are unit testing your async functions or doing integration tests, it's probably better to mock them anyway.