Difference between jest.mock and jest.doMock - testing

I want this to be specific to a single test:
it('should mock the module a single time', () => {
jest.doMock('../../../../../../../components/HighCharts/HighCharts', () => {
return () => <div id="mock-line-chart" />;
});
})
but it doesnt work. This works for the whole file:
jest.mock('../../../../../../../components/HighCharts/HighCharts', () => {
return () => <div id="my-special-div" />;
});
Am I not using this right? Where is the difference between doMock and mock. I it suitable to do a module mock for a single test only?

jest.mock is hoisted above import when used at top level and hoisted to the the beginning of the block when used in a block (test function scope, etc), same for jest.unmock. jest.doMock and jest.dontMock serve the same purpose but aren't hoisted.
This would matter for a case like this one:
it('should mock the module a single time', () => {
let originalHighCharts = require('.../HighCharts');
...
jest.doMock('.../HighCharts', ...);
let mockedHighCharts = require('.../HighCharts');
...
})
That doMock allows for specific order is rarely useful in practice because mocked module can be retrieved with jest.requireActual, while the same sequence may not affect other modules that depend on mocked module because of caching.
That doMock and dontMock aren't hoisted allows to use them together for a specified scenario to mock a module for single test:
let HighCharts;
jest.isolateModules(() => {
jest.doMock('.../HighCharts', ...);;
HighCharts = require('.../HighCharts');
jest.dontMock('.../HighCharts');
});
The downside is that dontMock may not be executed if the import fails, so it can affect other tests, this needs to be additionally handled. It may be more straightforward to enforce default module state that is preferable for most tests:
beforeEach(() => {
jest.unmock('.../HighCharts');
jest.resetModules();
});

Related

Testcafe data driven testing - how to drive tests with data fetched from API

I'm having trouble figuring out how to drive tests with data fetched from a request. I've read the documentation here: https://testcafe.io/documentation/402804/recipes/best-practices/create-data-driven-tests, and all examples use static json file data available at compile time.
I can't fetch the data in fixture.before hook, because it will only be available inside of the test context, but I need to access the data outside of the test context for iteration, such that the test is inside of a for loop.
I've tried this solution: https://github.com/DevExpress/testcafe/issues/1948, however this fails with testcafe ERROR No tests found in the specified source files. Ensure the sources contain the 'fixture' and 'test' directives., even when I use the flag disable-test-syntax-validation and .run({ disableTestSyntaxValidation: true }); option.
I am looking for suggestions and workarounds so that I can await some data, then run my tests. Even if Testcafe doesn't explicitly support something like this, I figure there must be some workaround... Thanks in advance.
Edit:
file-a.ts
export function tSteps(...args) {
// some setup
const testcase = args[args.length - 1];
const testCtx = test(name, async t => {
...
});
return testCtx;
}
----
file-b.ts
export const parameterizedTest = <T>(..., testcase: (scenario: T) => TestFn) => {
// some setup...
// I have also tried awaiting rows data here, which does not work
// because tests are not discoverable at compile time
...
const scenarios: T[] = rows.map(row => {
...
});
scenarios.forEach((scenario, idx) => {
return testcase(scenario).meta({
some metadata
});
});
};
----
tests.ts
fixture(...).before(async () => {
// can't get the data i need here because it needs to be available outside of the fixture context
})
parameterizedTest<MyInterface>(some params, (scenario: MyInterface) => {
return tSteps('my test',
async f => {
// some setup
// test code goes here which uses scenario.attributex, scenario.attributey, etc.
}
).meta(...);
}
);
In v1.0.0 and later, TestCafe does not validate test syntax. Please specify the TestCafe version that you use when you see the validation error.
Unfortunately, we cannot use pseudo-code to reproduce the issue you encountered. Please share some code that we could run to see the problematic behavior.
Generally speaking, TestCafe allows you to fetch data asynchronously and then spawn tests based on the received values. For instance, the following code works fine for me with TestCafe 1.18.3:
import { fixture, test } from 'testcafe';
import fetch from './node-fetch-mock';
(async () => {
const testData = await fetch();
testData
.map(n => () => {
fixture `Fixture ${n}`
.page `https://google.com`;
test(`Test ${n}`, async t => {
await t.expect(true).ok();
});
})
.map(async test => { await test(); });
})();
node-fetch-mock.js
export default async function fetch() {
return [1, 2, 3, 4, 5];
}
The only caveat is that I have to import fixture and test explicitly because I call them from callbacks.
Could you please provide us with any test code snippet that demonstrates the problem? We need to correctly understand the cause of the problem and reproduce it on our side.

How can I properly access store actions in a Vue test?

I have a test that is passing, but I don't understand why I have to write this way. Here is the test setup:
describe("Photo Due", () => {
const localVue = createLocalVue();
localVue.use(Vuex);
let store;
let actions = {
"api_data/photoAction": jest.fn(),
"api_data/selectPhoto": jest.fn(),
"modals/openCloseModal": jest.fn()
},
beforeEach(() => {
store = new Vuex.Store({
state: {
token: "abc",
GLN: "123",
GLT: "456",
isDesktop: true
},
getters: {
"auth/getToken": state => state.token,
"auth/getGLN": state => state.GLN,
"auth/getGLT": state => state.GLT,
"app/getIsDesktop": state => state.isDesktop
},
actions
});
});
...
Here is my test that calls a function, which calls an action:
it("reportPhoto", async () => {
const wrapper = factory();
wrapper.vm.reportPhoto();
wrapper.vm.$nextTick();
expect(actions["api_data/selectPhoto"]).toHaveBeenCalled(); // THIS IS THE LINE IN QUESTION
});
When the test is setup this way everything passes. But it doesn't seem right that I am defining actions outside of the store and accessing it that way in the test by calling actions["api_data/selectSnap"]. I copied this approach from a guide on from the vue-test-utils website. If I don't need to access actions and getters from the store then why not bypass the store altogether and jut define random functions that mock my vuex functionality?
I think I don't understand what is happening under the hood fully, but shouldn't I be accessing the action through the store? This is what I am having trouble doing.
My questions are 1) Do I need to access the actions through the store or am I overthinking what should be a basic test? 2) If I do need to access the action through the store, how do I go about doing that?
It really depends on what kind of test you are trying to do and if you want to test a fully functional store or just check that it gets called.
I recommend this post. There are differents approach explained along with several examples. It helped me when I needed to write some store oriented unit tests

Jest + puppeteer best architecture practices

I just entered the world of testing with puppeteer and jest, and I was wondering what the best practice was in terms of folder architecture and logic.
I've never done testing before and I think I'm getting a little lost in the different principles and concepts and how it all fits together.
I learned to do my tests based on the page-object model, so I have classes for each of my pages, but also for each of my modules ( or components ). For example, in my application, the header or the login modal are components.
Then I have a test file per page or per component.
(for example the landingPage.tests.js file, which uses the model of the LandingPage class in the LandingPage.js file)
Here is a concrete example:
I have different login cases and I'd like to test them all. For example I want to test to connect with a "normal" user, for which the process is simply login then password. Then I need to test with a user who has activated 2FA, or with a user from a company that uses SSO.
I first thought about putting my different tests in authentication.tests.js, in different describe blocks, thinking it would open a new tab each time, but it doesn't... I use puppeteer in incognito mode to make sure each tab is an isolated session.
So my questions are:
Where is the best place to do these test suites?
Am I supposed to have test files that "describe" the pages ( for example, the button must be present, such text must be here etc) and also have "scenario type" test file ( a set of contextual actions to a user, like for my different login cases) ?
Here is authentication.tests.js, in which I would like to tests all my different ways of logging in :
import HeaderComponent from "../../../pages/components/HeaderComponent";
import AuthenticationComponent from "../../../pages/components/AuthenticationComponent";
import LandingPage from "../../../pages/landing/LandingPage";
import {
JEST_TIMEOUT,
CREDENTIALS
} from "../../../config";
describe('Component:Authentication', () => {
let headerComponent;
let authenticationComponent;
let landingPage;
beforeAll(async () => {
jest.setTimeout(JEST_TIMEOUT);
headerComponent = new HeaderComponent;
authenticationComponent = new AuthenticationComponent;
landingPage = new LandingPage;
});
describe('Normal login ', () => {
it('should click on login and open modal', async () => {
await landingPage.visit();
await headerComponent.isVisible();
await headerComponent.clickOnLogin();
await authenticationComponent.isVisible();
});
it('should type a normal user email adress and validate', async () => {
await authenticationComponent.typeUsername(CREDENTIALS.normal.username);
await authenticationComponent.clickNext();
});
it('should type the correct password and validate', async () => {
await authenticationComponent.typePassword(CREDENTIALS.normal.password);
await authenticationComponent.clickNext();
});
it('should be logged in', async () => {
await waitForText(page, 'body', 'Success !');
});
});
describe('SSO login ', () => {
// todo ...
});
});
Thank you and sorry if it sounds confusing, like I said I'm trying to figure out how it all fits together.
Regarding the folder structure, Jest will find any files according to the match config, basically anything called *.spec.js or *.test.js. Looks like you know that already.
What that means is the folder structure is completely up to you. Some people like to have the tests for components in the same folders as the components themselves. Personally I prefer to have all the tests in one folder as it makes the project look cleaner.
The other benefit of having all the tests in one folder is that you can then start to distinguish between the types of tests. Component tests check that pure components render and operate as expected. You don't need Puppeteer for this, use snapshots if you're in a React app. Puppeteer is good for integration tests that navigate through so-called 'happy paths', login, signup, add to cart etc., using a headless Chromium browser.
To answer the specific problem you have been having with Jest / Puppeteer on a new page for each test:
//keep a reference to the browser
let browser
//keep a reference to the page
let page
// open puppeteer before all tests
beforeAll(async () => {
browser = await puppeteer.launch()
})
// close puppeteer after all tests
afterAll(async () => {
await browser.close()
})
// Get a new page for each test so that we start fresh.
beforeEach(async () => {
page = await browser.newPage()
})
// Remember to close pages after each test.
afterEach(async () => {
await page.close()
})
describe('Counter', () => {
// "it" blocks go here.
})
Hope that helps a bit.

Nuxt/Vuejs - How to create utils that have access to modules?

I am using asiox/vuejs to create a webpage. However I want to compartmentalize the code more. One example is I use axios to make requests to the backend, and the data in the response is commited into vuex.
this.$axios.get('events').then((response) => {
this.$store.commit('data/populate', response.data)
})
.catch((e) => {
console.error(e)
})
I want to write a util method for this, like this.$populate.events()
I have tried creating utils inside the plugins/ directory, but they dont have access to this.$axios or this.$store
Note that I have axios and vuex imported in nuxt.config.js
How can this be achieved?
If you need the function in the context, Vue instances and maybe even
in the Vuex store, you can use the inject function, which is the
second parameter of the plugins exported function.
Injecting content into Vue instances works similar to when doing this
in standard Vue apps. The $ will be prepended automatically to the
function.
Reference
export default ({ app, store }, inject) => {
inject("populate", () => {
app.$axios
.get("events")
.then(response => {
store.commit("data/populate", response.data);
})
.catch(e => {
console.error(e);
});
});
};
app variable is context property.
The root Vue instance options that includes all your plugins. For
example, when using axios, you can get access to $axios through
context.app.$axios.
Figured it out not 5 minutes after posting ...
Basically use this nuxt guide
And replace this with app in the method you'd like to move

How to dynamically mock ES6 modules with SystemJS?

I have a single-page application written in ES6. The code in transpiled server-side into classic javascript by babelJs, then loaded by SystemJs.
Javascript present in my html file:
System.config({
baseURL: '/js',
meta: {
'/js/*': { format: 'cjs' }
}});
System.defaultJSExtensions = true;
System.import("index.js")
.catch(function (error) {
console.error(error)
});
index.js:
import f1 from 'file1';
import f2 from 'file2';
// code here ...
Everything works fine. index.js is loaded, and all import statements are correctly executed.
Now, I want to create some pages with mocked ES6 modules, for testing purpose. My goal is to display pages by replacing model classes (contained in ES6 modules) with other static test classes.
Let's say I have 3 files: real_model.js, fake_model.js and component.js. component.js import the real model (import Model from 'real_model';).
How can I replace the real model by the fake one (in the component) dynamically ?
It's been a while since this question was posted, but maybe this solution might still be of help to anyone else.
With SystemJS it is possible to create a module on-the-fly using System.newModule. Then you can use System.set to overwrite existing modules with the new one. In our tests we use the following helper function to mock existing modules:
function mockModule(name, value) {
const normalizedName = System.normalizeSync(name);
System.delete(normalizedName);
System.set(normalizedName, System.newModule(Object.assign({ default: value }, value)));
}
Then, e.g. inside the beforeEach callback, we assign the mock and then import the module to be tested using System.import:
let [component, fake_model] = [];
beforeEach(() => {
// define mock
fake_model = { foo: 'bar' };
// overwrite module with mock
mockModule('real_model', fake_model);
// delete and reimport module
System.delete(System.normalizeSync('component'));
return System.import('src/testing').then((m) => {
component = m.default;
}).catch(err => console.error(err));
});
// test your component here ...
A big advantage of this approach is that you don't need an additional mocking library and it works solely with SystemJS.