test: add TypeScript module specs to examples

examples/js-with-babel/jest-esm-isolated.config.js

@@ -1,8 +1,27 @@
 /** @type {import('ts-jest').JestConfigWithTsJest} */
 module.exports = {
   preset: 'ts-jest/presets/js-with-babel-esm',
+
+  // #region support for .mts files as an extension
+  // moduleFileExtensions: [
+  //   "js",
+  //   "mjs",
+  //   "cjs",
+  //   "jsx",
+  //   "ts",
+  //   "tsx",
+  //   "json",
+  //   "node"
+  // ],
+  moduleFileExtensions: ['js', 'ts', 'mts'],
+
+  resolver: '<rootDir>/mjs-resolver.ts',
+  testMatch: ['**/__tests__/**/*.(m)?[jt]s?(x)', '**/?(*.)+(spec|test).(m)?[tj]s?(x)'],
+  // #endregion support for .mts files as an extension
+
   transform: {
-    '^.+\\.tsx?$': [
+    // m? for modules
+    '^.+\\.m?tsx?$': [
       'ts-jest',
       {
         babelConfig: true,

examples/js-with-babel/jest-esm.config.js

@@ -1,8 +1,27 @@
 /** @type {import('ts-jest').JestConfigWithTsJest} */
 module.exports = {
   preset: 'ts-jest/presets/js-with-babel-esm',
+
+  // #region support for .mts files as an extension
+  // moduleFileExtensions: [
+  //   "js",
+  //   "mjs",
+  //   "cjs",
+  //   "jsx",
+  //   "ts",
+  //   "tsx",
+  //   "json",
+  //   "node"
+  // ],
+  moduleFileExtensions: ['js', 'ts', 'mts'],
+
+  resolver: '<rootDir>/mjs-resolver.ts',
+  testMatch: ['**/__tests__/**/*.(m)?[jt]s?(x)', '**/?(*.)+(spec|test).(m)?[tj]s?(x)'],
+  // #endregion support for .mts files as an extension
+
   transform: {
-    '^.+\\.tsx?$': [
+    // m? for modules
+    '^.+\\.m?tsx?$': [
       'ts-jest',
       {
         babelConfig: true,

examples/js-with-babel/jest-isolated.config.js

@@ -1,8 +1,27 @@
 /** @type {import('ts-jest').JestConfigWithTsJest} */
 module.exports = {
   preset: 'ts-jest/presets/js-with-babel',
+
+  // #region support for .mts files as an extension
+  // moduleFileExtensions: [
+  //   "js",
+  //   "mjs",
+  //   "cjs",
+  //   "jsx",
+  //   "ts",
+  //   "tsx",
+  //   "json",
+  //   "node"
+  // ],
+  moduleFileExtensions: ['js', 'ts', 'mts'],
+
+  resolver: '<rootDir>/mjs-resolver.ts',
+  testMatch: ['**/__tests__/**/*.(m)?[jt]s?(x)', '**/?(*.)+(spec|test).(m)?[tj]s?(x)'],
+  // #endregion support for .mts files as an extension
+
   transform: {
-    '^.+\\.tsx?$': [
+    // m? for modules
+    '^.+\\.m?tsx?$': [
       'ts-jest',
       {
         babelConfig: true,

examples/js-with-babel/jest.config.js

@@ -1,8 +1,27 @@
 /** @type {import('ts-jest').JestConfigWithTsJest} */
 module.exports = {
   preset: 'ts-jest/presets/js-with-babel',
+
+  // #region support for .mts files as an extension
+  // moduleFileExtensions: [
+  //   "js",
+  //   "mjs",
+  //   "cjs",
+  //   "jsx",
+  //   "ts",
+  //   "tsx",
+  //   "json",
+  //   "node"
+  // ],
+  moduleFileExtensions: ['js', 'ts', 'mts'],
+
+  resolver: '<rootDir>/mjs-resolver.ts',
+  testMatch: ['**/__tests__/**/*.(m)?[jt]s?(x)', '**/?(*.)+(spec|test).(m)?[tj]s?(x)'],
+  // #endregion support for .mts files as an extension
+
   transform: {
-    '^.+\\.tsx?$': [
+    // m? for modules
+    '^.+\\.m?tsx?$': [
       'ts-jest',
       {
         babelConfig: true,

examples/js-with-babel/mjs-resolver.ts

@@ -0,0 +1,35 @@
+void `
+type ModuleResolverOptions = {
+  readonly conditions: unknown
+  defaultResolver(path: string, options: Readonly<ModuleResolverOptions>): ModuleResolver
+  rootDir: unknown
+
+  /** @see {@link https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/resolve/index.d.ts}, interface Opts */
+  readonly baseDir: string
+  extensions: string | readonly string[] | undefined
+  moduleDirectory: string | undefined
+  paths: string | readonly string[] | undefined
+}
+
+type ModuleResolver = (
+  path: string,
+  options: Readonly<ModuleResolverOptions>,
+) => ModuleResolverOptions['defaultResolver']
+`
+
+const mjsResolver /*: ModuleResolver */ = function (path, options) {
+  const mjsExtRegex = /\.mjs$/i
+
+  const resolver = options.defaultResolver
+  if (mjsExtRegex.test(path)) {
+    try {
+      return resolver(path.replace(mjsExtRegex, '.mts'), options)
+    } catch {
+      // use default resolver
+    }
+  }
+
+  return resolver(path, options)
+}
+
+module.exports = mjsResolver

examples/js-with-babel/src/welcome-message-module.spec.mts

@@ -0,0 +1,11 @@
+import { getWelcomeMessage } from './welcome-message'
+import welcomePerson from './welcome-person'
+
+test('module: should show welcome message', () => {
+  expect(getWelcomeMessage()).toMatchInlineSnapshot(`"Welcome to ts-jest!!!"`)
+})
+
+test('module: should show welcome person message', () => {
+  // @ts-expect-error in ESM mode, `default` is kept after compilation
+  expect(welcomePerson.default ? welcomePerson.default : welcomePerson).toMatchInlineSnapshot(`"Welcome to ts-jest!!!"`)
+})

examples/js-with-ts/jest-esm-isolated.config.js

@@ -1,7 +1,26 @@
 /** @type {import('ts-jest').JestConfigWithTsJest} */
 module.exports = {
   preset: 'ts-jest/presets/js-with-ts-esm',
+
+  // #region support for .mts files as an extension
+  // moduleFileExtensions: [
+  //   "js",
+  //   "mjs",
+  //   "cjs",
+  //   "jsx",
+  //   "ts",
+  //   "tsx",
+  //   "json",
+  //   "node"
+  // ],
+  moduleFileExtensions: ['js', 'ts', 'mts'],
+
+  resolver: '<rootDir>/mjs-resolver.ts',
+  testMatch: ['**/__tests__/**/*.(m)?[jt]s?(x)', '**/?(*.)+(spec|test).(m)?[tj]s?(x)'],
+  // #endregion support for .mts files as an extension
+
   transform: {
+    // m? for modules
     '^.+\\.m?[tj]sx?$': [
       'ts-jest',
       {

examples/js-with-ts/jest-esm.config.js

@@ -1,7 +1,26 @@
 /** @type {import('ts-jest').JestConfigWithTsJest} */
 module.exports = {
   preset: 'ts-jest/presets/js-with-ts-esm',
+
+  // #region support for .mts files as an extension
+  // moduleFileExtensions: [
+  //   "js",
+  //   "mjs",
+  //   "cjs",
+  //   "jsx",
+  //   "ts",
+  //   "tsx",
+  //   "json",
+  //   "node"
+  // ],
+  moduleFileExtensions: ['js', 'ts', 'mts'],
+
+  resolver: '<rootDir>/mjs-resolver.ts',
+  testMatch: ['**/__tests__/**/*.(m)?[jt]s?(x)', '**/?(*.)+(spec|test).(m)?[tj]s?(x)'],
+  // #endregion support for .mts files as an extension
+
   transform: {
+    // m? for modules
     '^.+\\.m?[tj]sx?$': [
       'ts-jest',
       {

examples/js-with-ts/jest-isolated.config.js

@@ -1,8 +1,27 @@
 /** @type {import('ts-jest').JestConfigWithTsJest} */
 module.exports = {
   preset: 'ts-jest/presets/js-with-ts',
+
+  // #region support for .mts files as an extension
+  // moduleFileExtensions: [
+  //   "js",
+  //   "mjs",
+  //   "cjs",
+  //   "jsx",
+  //   "ts",
+  //   "tsx",
+  //   "json",
+  //   "node"
+  // ],
+  moduleFileExtensions: ['js', 'ts', 'mts'],
+
+  resolver: '<rootDir>/mjs-resolver.ts',
+  testMatch: ['**/__tests__/**/*.(m)?[jt]s?(x)', '**/?(*.)+(spec|test).(m)?[tj]s?(x)'],
+  // #endregion support for .mts files as an extension
+
   transform: {
-    '^.+\\.[tj]sx?$': [
+    // m? for modules
+    '^.+\\.m?[tj]sx?$': [
       'ts-jest',
       {
         isolatedModules: true,

examples/js-with-ts/jest.config.js

@@ -1,4 +1,25 @@
 /** @type {import('ts-jest').JestConfigWithTsJest} */
 module.exports = {
   preset: 'ts-jest/presets/js-with-ts',
+
+  // #region support for .mts files as an extension
+  // moduleFileExtensions: [
+  //   "js",
+  //   "mjs",
+  //   "cjs",
+  //   "jsx",
+  //   "ts",
+  //   "tsx",
+  //   "json",
+  //   "node"
+  // ],
+  moduleFileExtensions: ['js', 'ts', 'mts'],
+
+  resolver: '<rootDir>/mjs-resolver.ts',
+  testMatch: ['**/__tests__/**/*.(m)?[jt]s?(x)', '**/?(*.)+(spec|test).(m)?[tj]s?(x)'],
+
+  transform: {
+    '^.+\\.mtsx?$': ['ts-jest'],
+  },
+  // #endregion support for .mts files as an extension
 }

examples/js-with-ts/mjs-resolver.ts

@@ -0,0 +1,35 @@
+void `
+type ModuleResolverOptions = {
+  readonly conditions: unknown
+  defaultResolver(path: string, options: Readonly<ModuleResolverOptions>): ModuleResolver
+  rootDir: unknown
+
+  /** @see {@link https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/resolve/index.d.ts}, interface Opts */
+  readonly baseDir: string
+  extensions: string | readonly string[] | undefined
+  moduleDirectory: string | undefined
+  paths: string | readonly string[] | undefined
+}
+
+type ModuleResolver = (
+  path: string,
+  options: Readonly<ModuleResolverOptions>,
+) => ModuleResolverOptions['defaultResolver']
+`
+
+const mjsResolver /*: ModuleResolver */ = function (path, options) {
+  const mjsExtRegex = /\.mjs$/i
+
+  const resolver = options.defaultResolver
+  if (mjsExtRegex.test(path)) {
+    try {
+      return resolver(path.replace(mjsExtRegex, '.mts'), options)
+    } catch {
+      // use default resolver
+    }
+  }
+
+  return resolver(path, options)
+}
+
+module.exports = mjsResolver

examples/js-with-ts/src/welcome-message-module.spec.mts

@@ -0,0 +1,11 @@
+import { getWelcomeMessage } from './welcome-message'
+import welcomePerson from './welcome-person'
+
+test('module: should show welcome message', () => {
+  expect(getWelcomeMessage()).toMatchInlineSnapshot(`"Welcome to ts-jest!!!"`)
+})
+
+test('module: should show welcome person message', () => {
+  // @ts-expect-error in ESM mode, `default` is kept after compilation
+  expect(welcomePerson.default ? welcomePerson.default : welcomePerson).toMatchInlineSnapshot(`"Welcome to ts-jest!!!"`)
+})

examples/ts-only/jest-esm-isolated.config.js

@@ -1,8 +1,27 @@
 /** @type {import('ts-jest').JestConfigWithTsJest} */
 module.exports = {
   preset: 'ts-jest/presets/default-esm',
+
+  // #region support for .mts files as an extension
+  // moduleFileExtensions: [
+  //   "js",
+  //   "mjs",
+  //   "cjs",
+  //   "jsx",
+  //   "ts",
+  //   "tsx",
+  //   "json",
+  //   "node"
+  // ],
+  moduleFileExtensions: ['js', 'ts', 'mts'],
+
+  resolver: '<rootDir>/mjs-resolver.ts',
+  testMatch: ['**/__tests__/**/*.(m)?[jt]s?(x)', '**/?(*.)+(spec|test).(m)?[tj]s?(x)'],
+  // #endregion support for .mts files as an extension
+
   transform: {
-    '^.+\\.tsx?$': [
+    // m? for modules
+    '^.+\\.m?tsx?$': [
       'ts-jest',
       {
         isolatedModules: true,

examples/ts-only/jest-esm.config.js

@@ -1,8 +1,27 @@
 /** @type {import('ts-jest').JestConfigWithTsJest} */
 module.exports = {
   preset: 'ts-jest/presets/default-esm',
+
+  // #region support for .mts files as an extension
+  // moduleFileExtensions: [
+  //   "js",
+  //   "mjs",
+  //   "cjs",
+  //   "jsx",
+  //   "ts",
+  //   "tsx",
+  //   "json",
+  //   "node"
+  // ],
+  moduleFileExtensions: ['js', 'ts', 'mts'],
+
+  resolver: '<rootDir>/mjs-resolver.ts',
+  testMatch: ['**/__tests__/**/*.(m)?[jt]s?(x)', '**/?(*.)+(spec|test).(m)?[tj]s?(x)'],
+  // #endregion support for .mts files as an extension
+
   transform: {
-    '^.+\\.tsx?$': [
+    // m? for modules
+    '^.+\\.m?tsx?$': [
       'ts-jest',
       {
         tsconfig: 'tsconfig-esm.json',