docs: how to use with testing frameworks (#1623)

Author: brenno263

docs/.vitepress/config.ts

@@ -193,6 +193,10 @@ const config = defineConfig({
             text: 'Localization',
             link: '/guide/localization',
           },
+          {
+            text: 'Frameworks',
+            link: '/guide/frameworks',
+          },
           {
             text: 'Upgrading to v8',
             link: '/guide/upgrading',

docs/guide/frameworks.md

@@ -0,0 +1,100 @@
+# Frameworks
+
+Faker can easily be used with a variety of testing frameworks. Here are a few examples with popular frameworks.
+
+Note that these examples use only the `en` locale for better performance. For more information visit [localization](./localization.md).
+
+## Vitest and Jest
+
+Since [Vitest](https://vitest.dev/) and [Jest](https://jestjs.io/) use an extremely similar notation, this section will cover both at once.
+The main difference is that testing methods need to be imported in Vitest.
+Simply crop that line out for a Jest integration.
+
+These frameworks work about exactly as you would expect with Faker. Here's a minimal example:
+
+```ts
+import { describe, it, expect } from 'vitest';
+import { faker } from '@faker-js/faker/locale/en';
+
+describe('reverse array', () => {
+  it('should reverse the array', () => {
+    const title = faker.name.jobTitle();
+    const name = faker.name.fullName();
+    const animal = faker.animal.bear();
+
+    const array = [title, name, animal];
+
+    expect(array.reverse()).toStrictEqual([animal, name, title]);
+  });
+});
+```
+
+It can sometimes be useful to do seeded tests, where we seed our faker instance with a static value so that it will generate the same random value each time.
+These are especially useful in tests that are meant to be deterministic, such as snapshot tests.
+
+- [Snapshots in Vitest](https://vitest.dev/guide/snapshot.html)
+- [Snapshots in Jest](https://jestjs.io/docs/snapshot-testing)
+
+```ts
+import { describe, it, expect } from 'vitest';
+import { faker } from '@faker-js/faker/locale/en';
+
+// We might want other tests to *not* be seeded. This will re-seed our faker instance after each test.
+afterEach(() => {
+  faker.seed();
+});
+
+describe('reverse array', () => {
+  it('should reverse the array', () => {
+    // Seed our faker instance with some static number.
+    faker.seed(1234);
+    const title = faker.name.jobTitle();
+    const name = faker.name.fullName();
+    const animal = faker.animal.bear();
+
+    const array = [title, name, animal];
+
+    expect(array.reverse()).toStrictEqual([animal, name, title]);
+
+    // Expect our value to always match a generated snapshot.
+    expect(array.reverse()).toMatchSnapshot();
+  });
+});
+```
+
+## Cypress
+
+[Cypress](https://www.cypress.io/) integration is fairly straighforward as well:
+
+```ts
+import { faker } from '@faker-js/faker/locale/en';
+
+describe('Testing the application', () => {
+  it('should create an account with username and password', () => {
+    let username = faker.internet.userName();
+    let password = faker.internet.password();
+    let email = faker.internet.exampleEmail();
+
+    // Visit the a webpage and create an account.
+    cy.visit('https://www.example.com/register');
+
+    cy.get('#email-input').type(email);
+    cy.get('#username-input').type(username);
+    cy.get('#password-input').type(password);
+    cy.get('#password-confirm-input').type(password);
+
+    cy.get('#register-submit-input').click();
+
+    // Now, we try to login with these credentials.
+    cy.visit('https://www.example.com/login');
+
+    cy.get('#email-input').type(email);
+    cy.get('#password-input').type(password);
+
+    cy.get('#login-submit-input').click();
+
+    // We should have logged in successfully to the dashboard page.
+    cy.url().should('include', '/dashboard');
+  });
+});
+```