, , , , ,

thumbnail

How to setup jest typescript with code runner in vscode

with this technique you can directly run test single file in vscode without typings manually in terminal, see below screenshot
image

Requirements

Setup

step by step how to setup jest within vscode code runner

create file .vscode/settings.json

create settings file and fill below configs.

{
  "emmet.includeLanguages": {
    "ejs": "html" // treat ejs as html
  },
  "terminal.integrated.env.linux": { // linux custom PATH environment variable
    "PATH": "${env:PATH}:${workspaceFolder}/node_modules/.bin:${workspaceFolder}/bin"
  },
  "terminal.integrated.env.windows": { // windows custom PATH environment variable
    "PATH": "${env:PATH};${workspaceFolder}\\node_modules\\.bin;${workspaceFolder}\\bin"
  },
  "editor.codeActionsOnSave": {
    "source.fixAll.eslint": true, // let ESLint take formating and linting
    "source.organizeImports": true // auto remove unused imports
  },
  "[ts]": {
    "editor.formatOnSave": false // custom formating with default vscode formatter
  },
  "[scss]": {
    "editor.formatOnSave": true, // custom formating with default vscode formatter
    "editor.defaultFormatter": "esbenp.prettier-vscode"
  },
  "[css]": {
    "editor.formatOnSave": true, // custom formating with default vscode formatter
    "editor.defaultFormatter": "esbenp.prettier-vscode"
  },
  "[ejs]": {
    "editor.formatOnSave": true // custom formating with default vscode formatter
  },
  "[json]": {
    "editor.formatOnSave": true, // custom formating with default vscode formatter
    "editor.defaultFormatter": "vscode.json-language-features"
  },
  "editor.formatOnSave": false, // default vscode formatter
  "git.enabled": true, // enable git
  "code-runner.clearPreviousOutput": true, // code runner clear console when run code
  "code-runner.saveFileBeforeRun": true, // code runner save current file before run
  "code-runner.saveAllFilesBeforeRun": true, // code runner save all files before run
  "code-runner.runInTerminal": true, // code runner run in terminal
  "files.exclude": {
    "**/node_modules": true,
    "**/vendor": true
  },
  "code-runner.respectShebang": true, // code runner follow executor maps
  "code-runner.executorMapByGlob": { // code runner executor map by glob
    "*.test.ts": "yarn test -- $fileNameWithoutExt"
  },
  "eslint.codeActionsOnSave.mode": "all" // code runner save all files before run
}

install dependencies

npm install -D jest ts-jest jest-config jest-mock @jest/expect @jest/environment @jest/types @jest/globals
# or
yarn add -D jest ts-jest jest-config jest-mock @jest/expect @jest/environment @jest/types @jest/globals

create jest.config.ts in root project

create config for jest in root of project, fill and configure below codes as you wish:

import type { Config } from 'jest';
import { defaults } from 'jest-config';
import { join } from 'path';

/**
 * @type {import('jest').Config}
 * @see {@link https://jestjs.io/docs/configuration}
 * * how to run single test {@link https://stackoverflow.com/questions/28725955/how-do-i-test-a-single-file-using-jest}
 */
const config: Config = {
  // preset for typescript
  preset: 'ts-jest',
  // test environtment
  testEnvironment: 'node',
  // extension of modules
  moduleFileExtensions: [...defaults.moduleFileExtensions, 'mts'],
  // jest verbose
  verbose: false,
  // jest use cache
  cache: true,
  // jest cache directory
  cacheDirectory: join(__dirname, 'tmp/jest'),
  // collect coverage from src folder but ignore with negate patterns
  collectCoverageFrom: ['src/*.{js,ts}', '!**/node_modules/**', '!**/vendor/**', '!**/test/**', '!**/*.test.{js,ts}'],
  // test root directory
  roots: [`<rootDir>/test`],
  // ignore collect coverage from these patterns
  coveragePathIgnorePatterns: ['/node_modules/', '/dist/', '/tmp/', '/test/'],
  // test files with these patterns
  testMatch: [`**/__tests__/**/*.+(ts|tsx|js)`, `**/?(*.)+(spec|test).+(ts|tsx|js)`, `**/test/*.test.ts`],
  // transformer typescript
  transform: {
    '^.+\\.(ts|tsx)$': [
      'ts-jest',
      // required due to custom location of tsconfig.json configuration file
      // https://kulshekhar.github.io/ts-jest/docs/getting-started/options/tsconfig
      { tsconfig: './tsconfig.json' }
    ]
  },
  // detect memory leaks
  detectLeaks: true,
  // Automatically clear mock calls, instances, contexts and results before every test
  clearMocks: true,

  // Indicates whether the coverage information should be collected while executing the test
  collectCoverage: true,

  // An array of glob patterns indicating a set of files for which coverage information should be collected
  // collectCoverageFrom: undefined,

  // The directory where Jest should output its coverage files
  coverageDirectory: 'coverage',

  // An array of regexp pattern strings used to skip coverage collection
  // coveragePathIgnorePatterns: [
  //   "\\\\node_modules\\\\"
  // ],

  // Indicates which provider should be used to instrument code for coverage
  coverageProvider: 'v8'

  // A list of reporter names that Jest uses when writing coverage reports
  // coverageReporters: [
  //   "json",
  //   "text",
  //   "lcov",
  //   "clover"
  // ],
};

export default config;

create tsconfig.jest.json

create typescript config for jest in root of project folder, change typescript config for jest below as you wish:

{
  // custom schema (non-vscode environment)
  "$schema": "https://json.schemastore.org/tsconfig",
  // extends other typescript config file
  "extends": "./tsconfig.json",
  "compilerOptions": {
    // make dump output to temp folder
    "outDir": "tmp/jest",
    /* Visit https://aka.ms/tsconfig.json to read more about this file */
    /* Language and Environment */
    "target": "es2016" /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */,

    /* Modules */
    "module": "commonjs" /* Specify what module code is generated. */,
    "esModuleInterop": true /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables `allowSyntheticDefaultImports` for type compatibility. */,
    "forceConsistentCasingInFileNames": true /* Ensure that casing is correct in imports. */,

    /* Type Checking */
    "strict": false /* Enable all strict type-checking */,
    "skipLibCheck": true /* Skip type checking all .d.ts files. */
  }
}

step to test

create sample test inside test folder

create test/math-operator.test.ts

create sample math operator test for jest, below is sample test:

import { beforeEach, describe, expect, it, jest } from '@jest/globals';

const mathOperations = {
   sum: function(a,b) {
       return a + b;
   },
   
   diff: function(a,b) {
       return a - b;
   },
   product: function(a,b) {
       return a * b
   }
}

describe("Calculator tests", () => {
 jest.setTimeout(60000); // sample set timeout globally
 test('adding 1 + 2 should return 3', () => {
   expect(mathOperations.sum(1, 2)).toBe(3);
 });
})

to run above file, just right click choose run. Sample result below:
image

Conclusion

thats all how to setup jest typescript in vscode. above steps 100 percent tested in year 2023.