From 543b4ad729d20fbd46a2de5cd4660dc50b94ebe7 Mon Sep 17 00:00:00 2001
From: Ahn <27772165+ahnpnl@users.noreply.github.com>
Date: Wed, 27 Apr 2022 13:43:34 +0200
Subject: [PATCH] feat(presets): add presets for legacy mode (#3465)

---
 e2e/presets/__tests__/presets.spec.ts         | 35 ++++++++++++++++
 presets/default-esm-legacy/jest-preset.js     |  1 +
 presets/default-legacy/jest-preset.js         |  1 +
 presets/index.d.ts                            |  6 +++
 presets/index.js                              | 41 ++++++++++++++++---
 .../js-with-babel-esm-legacy/jest-preset.js   |  1 +
 presets/js-with-babel-legacy/jest-preset.js   |  1 +
 presets/js-with-ts-esm-legacy/jest-preset.js  |  1 +
 presets/js-with-ts-legacy/jest-preset.js      |  1 +
 src/index.ts                                  |  9 ++--
 src/legacy/index.ts                           |  2 -
 .../create-jest-preset.spec.ts.snap           |  8 ++--
 src/presets/create-jest-preset.spec.ts        |  9 +++-
 src/presets/create-jest-preset.ts             | 10 ++++-
 website/docs/getting-started/presets.md       | 28 +++++++++----
 website/docs/guides/esm-support.md            |  6 +++
 16 files changed, 134 insertions(+), 26 deletions(-)
 create mode 100644 presets/default-esm-legacy/jest-preset.js
 create mode 100644 presets/default-legacy/jest-preset.js
 create mode 100644 presets/js-with-babel-esm-legacy/jest-preset.js
 create mode 100644 presets/js-with-babel-legacy/jest-preset.js
 create mode 100644 presets/js-with-ts-esm-legacy/jest-preset.js
 create mode 100644 presets/js-with-ts-legacy/jest-preset.js

diff --git a/e2e/presets/__tests__/presets.spec.ts b/e2e/presets/__tests__/presets.spec.ts
index a97429dee9..6339be19ab 100644
--- a/e2e/presets/__tests__/presets.spec.ts
+++ b/e2e/presets/__tests__/presets.spec.ts
@@ -9,29 +9,57 @@ test('presets', () => {
       '^.+\\.tsx?$': 'ts-jest',
     },
   })
+  expect(presets.defaultsLegacy).toEqual({
+    transform: {
+      '^.+\\.tsx?$': 'ts-jest/legacy',
+    },
+  })
   expect(presets.defaultsESM).toEqual({
     extensionsToTreatAsEsm: [...TS_EXT_TO_TREAT_AS_ESM],
     transform: {
       '^.+\\.tsx?$': 'ts-jest',
     },
   })
+  expect(presets.defaultsESMLegacy).toEqual({
+    extensionsToTreatAsEsm: [...TS_EXT_TO_TREAT_AS_ESM],
+    transform: {
+      '^.+\\.tsx?$': 'ts-jest/legacy',
+    },
+  })
   expect(presets.jsWithTs).toEqual({
     transform: {
       '^.+\\.[tj]sx?$': 'ts-jest',
     },
   })
+  expect(presets.jsWithTsLegacy).toEqual({
+    transform: {
+      '^.+\\.[tj]sx?$': 'ts-jest/legacy',
+    },
+  })
   expect(presets.jsWithTsESM).toEqual({
     extensionsToTreatAsEsm: [...JS_EXT_TO_TREAT_AS_ESM, ...TS_EXT_TO_TREAT_AS_ESM],
     transform: {
       '^.+\\.m?[tj]sx?$': 'ts-jest',
     },
   })
+  expect(presets.jsWithTsESMLegacy).toEqual({
+    extensionsToTreatAsEsm: [...JS_EXT_TO_TREAT_AS_ESM, ...TS_EXT_TO_TREAT_AS_ESM],
+    transform: {
+      '^.+\\.m?[tj]sx?$': 'ts-jest/legacy',
+    },
+  })
   expect(presets.jsWithBabel).toEqual({
     transform: {
       '^.+\\.tsx?$': 'ts-jest',
       '^.+\\.jsx?$': 'babel-jest',
     },
   })
+  expect(presets.jsWithBabelLegacy).toEqual({
+    transform: {
+      '^.+\\.tsx?$': 'ts-jest/legacy',
+      '^.+\\.jsx?$': 'babel-jest',
+    },
+  })
   expect(presets.jsWithBabelESM).toEqual({
     extensionsToTreatAsEsm: [...JS_EXT_TO_TREAT_AS_ESM, ...TS_EXT_TO_TREAT_AS_ESM],
     transform: {
@@ -39,4 +67,11 @@ test('presets', () => {
       '^.+\\.m?[j]sx?$': 'babel-jest',
     },
   })
+  expect(presets.jsWithBabelESMLegacy).toEqual({
+    extensionsToTreatAsEsm: [...JS_EXT_TO_TREAT_AS_ESM, ...TS_EXT_TO_TREAT_AS_ESM],
+    transform: {
+      '^.+\\.tsx?$': 'ts-jest/legacy',
+      '^.+\\.m?[j]sx?$': 'babel-jest',
+    },
+  })
 })
diff --git a/presets/default-esm-legacy/jest-preset.js b/presets/default-esm-legacy/jest-preset.js
new file mode 100644
index 0000000000..e69ddb95c7
--- /dev/null
+++ b/presets/default-esm-legacy/jest-preset.js
@@ -0,0 +1 @@
+module.exports = require('..').defaultsESMLegacy
diff --git a/presets/default-legacy/jest-preset.js b/presets/default-legacy/jest-preset.js
new file mode 100644
index 0000000000..7b1cede23b
--- /dev/null
+++ b/presets/default-legacy/jest-preset.js
@@ -0,0 +1 @@
+module.exports = require('..').defaultsLegacy
diff --git a/presets/index.d.ts b/presets/index.d.ts
index c61abe9dd8..84383d9716 100644
--- a/presets/index.d.ts
+++ b/presets/index.d.ts
@@ -2,10 +2,16 @@ import type { TsJestPresets } from '../dist'
 
 declare const _default: {
     defaults: TsJestPresets;
+    defaultsLegacy: TsJestPresets;
     defaultsESM: TsJestPresets;
+    defaultsESMLegacy: TsJestPresets;
     jsWithTs: TsJestPresets;
+    jsWithTsLegacy: TsJestPresets;
     jsWithTsESM: TsJestPresets;
+    jsWithTsESMLegacy: TsJestPresets;
     jsWithBabel: TsJestPresets;
+    jsWithBabelLegacy: TsJestPresets;
     jsWithBabelESM: TsJestPresets;
+    jsWithBabelESMLegacy: TsJestPresets;
 };
 export = _default;
diff --git a/presets/index.js b/presets/index.js
index 07eedbbca6..b000651d2b 100644
--- a/presets/index.js
+++ b/presets/index.js
@@ -5,24 +5,55 @@ module.exports = {
   get defaults() {
     return createJestPreset()
   },
+  get defaultsLegacy() {
+    return createJestPreset(true, false)
+  },
   get defaultsESM() {
-    return createJestPreset(false, { extensionsToTreatAsEsm: TS_EXT_TO_TREAT_AS_ESM })
+    return createJestPreset(false, false, { extensionsToTreatAsEsm: TS_EXT_TO_TREAT_AS_ESM })
+  },
+  get defaultsESMLegacy() {
+    return createJestPreset(true, false, { extensionsToTreatAsEsm: TS_EXT_TO_TREAT_AS_ESM })
   },
   get jsWithTs() {
-    return createJestPreset(true)
+    return createJestPreset(false, true)
+  },
+  get jsWithTsLegacy() {
+    return createJestPreset(true, true)
   },
   get jsWithTsESM() {
-    return createJestPreset(true, { extensionsToTreatAsEsm: [...JS_EXT_TO_TREAT_AS_ESM, ...TS_EXT_TO_TREAT_AS_ESM] })
+    return createJestPreset(false, true, {
+      extensionsToTreatAsEsm: [...JS_EXT_TO_TREAT_AS_ESM, ...TS_EXT_TO_TREAT_AS_ESM],
+    })
+  },
+  get jsWithTsESMLegacy() {
+    return createJestPreset(true, true, {
+      extensionsToTreatAsEsm: [...JS_EXT_TO_TREAT_AS_ESM, ...TS_EXT_TO_TREAT_AS_ESM],
+    })
   },
   get jsWithBabel() {
-    return createJestPreset(false, {
+    return createJestPreset(false, false, {
+      transform: {
+        '^.+\\.jsx?$': 'babel-jest',
+      },
+    })
+  },
+  get jsWithBabelLegacy() {
+    return createJestPreset(true, false, {
       transform: {
         '^.+\\.jsx?$': 'babel-jest',
       },
     })
   },
   get jsWithBabelESM() {
-    return createJestPreset(false, {
+    return createJestPreset(false, false, {
+      extensionsToTreatAsEsm: [...JS_EXT_TO_TREAT_AS_ESM, ...TS_EXT_TO_TREAT_AS_ESM],
+      transform: {
+        '^.+\\.m?[j]sx?$': 'babel-jest',
+      },
+    })
+  },
+  get jsWithBabelESMLegacy() {
+    return createJestPreset(true, false, {
       extensionsToTreatAsEsm: [...JS_EXT_TO_TREAT_AS_ESM, ...TS_EXT_TO_TREAT_AS_ESM],
       transform: {
         '^.+\\.m?[j]sx?$': 'babel-jest',
diff --git a/presets/js-with-babel-esm-legacy/jest-preset.js b/presets/js-with-babel-esm-legacy/jest-preset.js
new file mode 100644
index 0000000000..33062408fc
--- /dev/null
+++ b/presets/js-with-babel-esm-legacy/jest-preset.js
@@ -0,0 +1 @@
+module.exports = require('..').jsWithBabelESMLegacy
diff --git a/presets/js-with-babel-legacy/jest-preset.js b/presets/js-with-babel-legacy/jest-preset.js
new file mode 100644
index 0000000000..a2d5ff8b3f
--- /dev/null
+++ b/presets/js-with-babel-legacy/jest-preset.js
@@ -0,0 +1 @@
+module.exports = require('..').jsWithBabelLegacy
diff --git a/presets/js-with-ts-esm-legacy/jest-preset.js b/presets/js-with-ts-esm-legacy/jest-preset.js
new file mode 100644
index 0000000000..592e02c962
--- /dev/null
+++ b/presets/js-with-ts-esm-legacy/jest-preset.js
@@ -0,0 +1 @@
+module.exports = require('..').jsWithTsESMLegacy
diff --git a/presets/js-with-ts-legacy/jest-preset.js b/presets/js-with-ts-legacy/jest-preset.js
new file mode 100644
index 0000000000..76cb70f0b9
--- /dev/null
+++ b/presets/js-with-ts-legacy/jest-preset.js
@@ -0,0 +1 @@
+module.exports = require('..').jsWithTsLegacy
diff --git a/src/index.ts b/src/index.ts
index 01267d7450..6e5eb70972 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,12 +1,13 @@
-import { TsJestTransformer } from './legacy'
+import { TsJestTransformer } from './legacy/ts-jest-transformer'
 
-export * from './legacy'
+export * from './config'
 export * from './constants'
 export * from './legacy/compiler'
-export * from './config'
+export * from './legacy/ts-jest-transformer'
+export * from './legacy/config/config-set'
 export * from './presets/create-jest-preset'
-export * from './utils'
 export * from './raw-compiler-options'
+export * from './utils'
 export * from './types'
 
 export default {
diff --git a/src/legacy/index.ts b/src/legacy/index.ts
index cd4424988c..9cfb6e5d73 100644
--- a/src/legacy/index.ts
+++ b/src/legacy/index.ts
@@ -1,7 +1,5 @@
 import { TsJestTransformer } from './ts-jest-transformer'
 
-export * from './ts-jest-transformer'
-
 export default {
   createTransformer: (): TsJestTransformer => new TsJestTransformer(),
 }
diff --git a/src/presets/__snapshots__/create-jest-preset.spec.ts.snap b/src/presets/__snapshots__/create-jest-preset.spec.ts.snap
index 2f8d12dbd7..7d28dbdb8b 100644
--- a/src/presets/__snapshots__/create-jest-preset.spec.ts.snap
+++ b/src/presets/__snapshots__/create-jest-preset.spec.ts.snap
@@ -3,7 +3,7 @@
 exports[`create-jest-preset should return correct preset 1`] = `
 Object {
   "transform": Object {
-    "^.+\\\\.tsx?$": "ts-jest",
+    "^.+\\\\.tsx?$": "ts-jest/legacy",
   },
 }
 `;
@@ -19,7 +19,7 @@ Object {
 exports[`create-jest-preset should return correct preset 3`] = `
 Object {
   "transform": Object {
-    "^.+\\\\.[tj]sx?$": "ts-jest",
+    "^.+\\\\.[tj]sx?$": "ts-jest/legacy",
   },
 }
 `;
@@ -35,7 +35,7 @@ Object {
 exports[`create-jest-preset should return correct preset 5`] = `
 Object {
   "transform": Object {
-    "^.+\\\\.tsx?$": "ts-jest",
+    "^.+\\\\.tsx?$": "ts-jest/legacy",
   },
 }
 `;
@@ -69,7 +69,7 @@ Object {
     "foo",
   ],
   "transform": Object {
-    "^.+\\\\.m?[tj]sx?$": "ts-jest",
+    "^.+\\\\.m?[tj]sx?$": "ts-jest/legacy",
     "foo": "bar",
   },
 }
diff --git a/src/presets/create-jest-preset.spec.ts b/src/presets/create-jest-preset.spec.ts
index e8267b8fda..a4b7d424da 100644
--- a/src/presets/create-jest-preset.spec.ts
+++ b/src/presets/create-jest-preset.spec.ts
@@ -11,30 +11,37 @@ describe('create-jest-preset', () => {
 
   test.each([
     {
+      legacy: true,
       allowJs: undefined,
       extraOptions: undefined,
     },
     {
+      legacy: false,
       allowJs: false,
       extraOptions: undefined,
     },
     {
+      legacy: true,
       allowJs: true,
       extraOptions: undefined,
     },
     {
+      legacy: false,
       allowJs: true,
       extraOptions: {},
     },
     {
+      legacy: true,
       allowJs: false,
       extraOptions: {},
     },
     {
+      legacy: false,
       allowJs: false,
       extraOptions: baseExtraOptions,
     },
     {
+      legacy: true,
       allowJs: true,
       extraOptions: {
         ...baseExtraOptions,
@@ -42,6 +49,6 @@ describe('create-jest-preset', () => {
       },
     },
   ])('should return correct preset', (data) => {
-    expect(createJestPreset(data.allowJs, data.extraOptions)).toMatchSnapshot()
+    expect(createJestPreset(data.legacy, data.allowJs, data.extraOptions)).toMatchSnapshot()
   })
 })
diff --git a/src/presets/create-jest-preset.ts b/src/presets/create-jest-preset.ts
index 0cf13af314..aff2cf649b 100644
--- a/src/presets/create-jest-preset.ts
+++ b/src/presets/create-jest-preset.ts
@@ -5,7 +5,11 @@ import { rootLogger } from '../utils'
 
 const logger = rootLogger.child({ namespace: 'jest-preset' })
 
-export function createJestPreset(allowJs = false, extraOptions: Config.InitialOptions = {}): TsJestPresets {
+export function createJestPreset(
+  legacy = false,
+  allowJs = false,
+  extraOptions: Config.InitialOptions = {},
+): TsJestPresets {
   logger.debug({ allowJs }, 'creating jest presets', allowJs ? 'handling' : 'not handling', 'JavaScript files')
 
   const { extensionsToTreatAsEsm, moduleFileExtensions, testMatch } = extraOptions
@@ -17,7 +21,9 @@ export function createJestPreset(allowJs = false, extraOptions: Config.InitialOp
     ...(testMatch ? { testMatch } : undefined),
     transform: {
       ...extraOptions.transform,
-      [allowJs ? (supportESM ? '^.+\\.m?[tj]sx?$' : '^.+\\.[tj]sx?$') : '^.+\\.tsx?$']: 'ts-jest',
+      [allowJs ? (supportESM ? '^.+\\.m?[tj]sx?$' : '^.+\\.[tj]sx?$') : '^.+\\.tsx?$']: legacy
+        ? 'ts-jest/legacy'
+        : 'ts-jest',
     },
   }
 }
diff --git a/website/docs/getting-started/presets.md b/website/docs/getting-started/presets.md
index be43edb499..6a70d9d03d 100644
--- a/website/docs/getting-started/presets.md
+++ b/website/docs/getting-started/presets.md
@@ -5,16 +5,28 @@ title: Presets
 
 ### The presets
 
+:::important
+
+Starting from **v28.0.0**, `ts-jest` will gradually switch to `esbuild`/`swc` to transform `ts` to `js`. To make the transition smoothly, we introduce `legacy` presets as a fallback when the new codes don't work yet.
+
+:::
+
 `ts-jest` comes with several presets, covering most of the project's base configuration:
 
-| Preset name                                | Description                                                                                                                                                                                         |
-| ------------------------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
-| `ts-jest/presets/default`<br/>or `ts-jest` | TypeScript files (`.ts`, `.tsx`) will be transformed by `ts-jest` to **CommonJS** syntax, leaving JavaScript files (`.js`, `jsx`) as-is.                                                            |
-| `ts-jest/presets/default-esm`<br/>         | TypeScript files (`.ts`, `.tsx`) will be transformed by `ts-jest` to **ESM** syntax, leaving JavaScript files (`.js`, `jsx`) as-is.                                                                 |
-| `ts-jest/presets/js-with-ts`               | TypeScript and JavaScript files (`.ts`, `.tsx`, `.js`, `.jsx`) will be transformed by `ts-jest` to **CommonJS** syntax.<br/>You'll need to set `allowJs` to `true` in your `tsconfig.json` file.    |
-| `ts-jest/presets/js-with-ts-esm`           | TypeScript and JavaScript files (`.ts`, `.tsx`, `.js`, `.jsx`, `.mjs`) will be transformed by `ts-jest` to **ESM** syntax.<br/>You'll need to set `allowJs` to `true` in your `tsconfig.json` file. |
-| `ts-jest/presets/js-with-babel`            | TypeScript files (`.ts`, `.tsx`) will be transformed by `ts-jest` to **CommonJS** syntax, and JavaScript files (`.js`, `jsx`) will be transformed by `babel-jest`.                                  |
-| `ts-jest/presets/js-with-babel-esm`        | TypeScript files (`.ts`, `.tsx`) will be transformed by `ts-jest` to **ESM** syntax, and JavaScript files (`.js`, `jsx`, `.mjs`) will be transformed by `babel-jest`.                               |
+| Preset name                                                           | Description                                                                                                                                                                                         |
+| --------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
+| `ts-jest/presets/default`<br/>or `ts-jest`                            | TypeScript files (`.ts`, `.tsx`) will be transformed by `ts-jest` to **CommonJS** syntax, leaving JavaScript files (`.js`, `jsx`) as-is.                                                            |
+| `ts-jest/presets/default-legacy`<br/>or `ts-jest/legacy` (**LEGACY**) | TypeScript files (`.ts`, `.tsx`) will be transformed by `ts-jest` to **CommonJS** syntax, leaving JavaScript files (`.js`, `jsx`) as-is.                                                            |
+| `ts-jest/presets/default-esm`<br/>                                    | TypeScript files (`.ts`, `.tsx`) will be transformed by `ts-jest` to **ESM** syntax, leaving JavaScript files (`.js`, `jsx`) as-is.                                                                 |
+| `ts-jest/presets/default-esm-legacy`<br/> (**LEGACY**)                | TypeScript files (`.ts`, `.tsx`) will be transformed by `ts-jest` to **ESM** syntax, leaving JavaScript files (`.js`, `jsx`) as-is.                                                                 |
+| `ts-jest/presets/js-with-ts`                                          | TypeScript and JavaScript files (`.ts`, `.tsx`, `.js`, `.jsx`) will be transformed by `ts-jest` to **CommonJS** syntax.<br/>You'll need to set `allowJs` to `true` in your `tsconfig.json` file.    |
+| `ts-jest/presets/js-with-ts-legacy` (**LEGACY**)                      | TypeScript and JavaScript files (`.ts`, `.tsx`, `.js`, `.jsx`) will be transformed by `ts-jest` to **CommonJS** syntax.<br/>You'll need to set `allowJs` to `true` in your `tsconfig.json` file.    |
+| `ts-jest/presets/js-with-ts-esm`                                      | TypeScript and JavaScript files (`.ts`, `.tsx`, `.js`, `.jsx`, `.mjs`) will be transformed by `ts-jest` to **ESM** syntax.<br/>You'll need to set `allowJs` to `true` in your `tsconfig.json` file. |
+| `ts-jest/presets/js-with-ts-esm-legacy` (**LEGACY**)                  | TypeScript and JavaScript files (`.ts`, `.tsx`, `.js`, `.jsx`, `.mjs`) will be transformed by `ts-jest` to **ESM** syntax.<br/>You'll need to set `allowJs` to `true` in your `tsconfig.json` file. |
+| `ts-jest/presets/js-with-babel`                                       | TypeScript files (`.ts`, `.tsx`) will be transformed by `ts-jest` to **CommonJS** syntax, and JavaScript files (`.js`, `jsx`) will be transformed by `babel-jest`.                                  |
+| `ts-jest/presets/js-with-babel-legacy` (**LEGACY**)                   | TypeScript files (`.ts`, `.tsx`) will be transformed by `ts-jest` to **CommonJS** syntax, and JavaScript files (`.js`, `jsx`) will be transformed by `babel-jest`.                                  |
+| `ts-jest/presets/js-with-babel-esm`                                   | TypeScript files (`.ts`, `.tsx`) will be transformed by `ts-jest` to **ESM** syntax, and JavaScript files (`.js`, `jsx`, `.mjs`) will be transformed by `babel-jest`.                               |
+| `ts-jest/presets/js-with-babel-esm-legacy` (**LEGACY**)               | TypeScript files (`.ts`, `.tsx`) will be transformed by `ts-jest` to **ESM** syntax, and JavaScript files (`.js`, `jsx`, `.mjs`) will be transformed by `babel-jest`.                               |
 
 ### Basic usage
 
diff --git a/website/docs/guides/esm-support.md b/website/docs/guides/esm-support.md
index e7a3ce2fbd..b9d0a36392 100644
--- a/website/docs/guides/esm-support.md
+++ b/website/docs/guides/esm-support.md
@@ -54,6 +54,12 @@ module.exports = {
 
 #### Use ESM presets
 
+:::important
+
+Starting from **v28.0.0**, `ts-jest` will gradually switch to `esbuild`/`swc` to transform `ts` to `js`. To make the transition smoothly, we introduce `legacy` presets as a fallback when the new codes don't work yet.
+
+:::
+
 ```js
 // jest.config.js
 module.exports = {