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Adding Vitest To An Existing Project

Vitest can be added to existing Angular workspaces with a few steps.

Using a Schematic/Generator​

Vitest can be installed and setup using a schematic/generator for Angular CLI or Nx workspaces.

First, install the @analogjs/platform package:

npm install @analogjs/platform --save-dev

Next, run the schematic to set up the Vite config, test configuration files, and update the test configuration.

ng g @analogjs/platform:setup-vitest --project [your-project-name]

Next, go to running tests

Manual Installation​

To add Vitest manually, install the necessary packages:

npm install @analogjs/vite-plugin-angular @analogjs/platform jsdom @nx/vite --save-dev

Setup for Running Tests for Node​

To setup Vitest, create a vite.config.ts at the root of your project:

/// <reference types="vitest" />
import { defineConfig } from 'vite';

import angular from '@analogjs/vite-plugin-angular';

export default defineConfig(({ mode }) => ({
  plugins: [angular()],
  test: {
    globals: true,
    setupFiles: ['src/test-setup.ts'],
    environment: 'jsdom',
    include: ['src/**/*.{test,spec}.{js,mjs,cjs,ts,mts,cts,jsx,tsx}'],
    reporters: ['default'],
  },
  define: {
    'import.meta.vitest': mode !== 'production',
  },
}));

Next, define a src/test-setup.ts file to setup the TestBed:

import '@analogjs/vite-plugin-angular/setup-vitest';

import {
  BrowserDynamicTestingModule,
  platformBrowserDynamicTesting,
} from '@angular/platform-browser-dynamic/testing';
import { getTestBed } from '@angular/core/testing';

getTestBed().initTestEnvironment(
  BrowserDynamicTestingModule,
  platformBrowserDynamicTesting()
);

Next, update the test target in the angular.json to use the @analogjs/platform:vitest builder:

{
  "$schema": "./node_modules/@angular/cli/lib/config/schema.json",
  "version": 1,
  "newProjectRoot": "projects",
  "projects": {
    "your-project": {
      "projectType": "application",
      "architect": {
        "build": ...,
        "serve": ...,
        "extract-i18n": ...,
        "test": {
          "builder": "@analogjs/platform:vitest"
        }
      }
    }
  }
}

You can also add a new target and name it vitest to run alongside your test target.

Lastly, add the src/test-setup.ts to files array in the tsconfig.spec.json in the root of your project, set the target to es2016, and update the types.

{
  "extends": "./tsconfig.json",
  "compilerOptions": {
    "outDir": "./out-tsc/spec",
    "target": "es2016",
    "types": ["vitest/globals", "node"]
  },
  "files": ["src/test-setup.ts"],
  "include": ["src/**/*.spec.ts", "src/**/*.d.ts"]
}

Next, go to running tests

Setup for Running Tests in the Browser​

If you prefer to run your tests in a browser, Vitest has experimental support for browser testing also.

First, follow the steps for running tests in node.

Then, install the necessary packages for running tests in the browser:

npm install @vitest/browser playwright --save-dev

Update the test object in the vite.config.ts.

  • Remove the environment: 'jsdom' property.
  • Add a browser config for Vitest.
/// <reference types="vitest" />
import { defineConfig } from 'vite';

import angular from '@analogjs/vite-plugin-angular';

export default defineConfig(({ mode }) => ({
  plugins: [angular()],
  test: {
    globals: true,
    setupFiles: ['src/test-setup.ts'],
    // environment: 'jsdom',
    include: ['src/**/*.{test,spec}.{js,mjs,cjs,ts,mts,cts,jsx,tsx}'],
    reporters: ['default'],
    // Vitest browser config
    browser: {
      enabled: true,
      name: 'chromium',
      headless: false, // set to true in CI
      provider: 'playwright',
    },
  },
  define: {
    'import.meta.vitest': mode !== 'production',
  },
}));

Running Tests​

To run unit tests, use the test command:

npm run test

Snapshot Testing​

For snapshot testing you can use toMatchSnapshot from expect API.

Below is a small example of how to write a snapshot test:

// card.component.spec.ts

import { ComponentFixture, TestBed } from '@angular/core/testing';

import { CardComponent } from './card.component';

describe('CardComponent', () => {
  let fixture: ComponentFixture<CardComponent>;
  let component: CardComponent;

  beforeEach(() =>
    TestBed.configureTestingModule({
      imports: [CardComponent],
    })
  );

  beforeEach(() => {
    fixture = TestBed.createComponent(CardComponent);
    component = fixture.componentInstance;
    fixture.detectChanges();
  });

  it('should create the app', () => {
    expect(fixture).toMatchSnapshot();
  });

After you run the test, a card.component.spec.ts.snap file is created in the__snapshots__ folder with the below content:

// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html

exports[`CardComponent > should create the app 1`] = `
  <component-code>
`;

The snapshots generated should be reviewed and added to version control.

Using TypeScript Config Path Aliases​

If you are using paths in your tsconfig.json, support for those aliases can be added to the vite.config.ts.

First, install the vite-tsconfig-paths package.

npm install vite-tsconfig-paths --save-dev

Next, add the plugin to the plugins array in the vite.config.ts with the root set as the relative path to the root of the project.

/// <reference types="vitest" />
import { defineConfig } from 'vite';

import angular from '@analogjs/vite-plugin-angular';
import viteTsConfigPaths from 'vite-tsconfig-paths';

export default defineConfig(({ mode }) => ({
  plugins: [angular(), viteTsConfigPaths()],
}));