Babel 8 compatibility

.github/workflows/ci.yml

@@ -44,6 +44,21 @@ jobs:
       - run: pnpm i --frozen-lockfile
       - run: pnpm test
 
+  test-babel-8:
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+
+    steps:
+      - uses: actions/checkout@v4
+      - uses: pnpm/action-setup@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22.x
+          cache: pnpm
+      - run: pnpm i
+      - run: pnpm i @babel/core@^8.0.0-0 @babel/plugin-syntax-decorators@^8.0.0-0 @babel/plugin-transform-typescript@^8.0.0-0 --save
+      - run: pnpm test
+
   floating:
     runs-on: ubuntu-latest
     timeout-minutes: 10

jest.config.js

@@ -1,5 +1,9 @@
 /** @type {import('ts-jest/dist/types').InitialOptionsTsJest} */
+
+const runNatively = !!process.features.typescript;
+
 module.exports = {
+  runner: runNatively ? 'jest-light-runner' : undefined,
   preset: 'ts-jest/presets/default-esm',
   testEnvironment: 'node',
   moduleDirectories: ['node_modules', 'src'],
@@ -9,6 +13,7 @@ module.exports = {
       diagnostics: {
         ignoreCodes: [151001],
       },
+      useESM: runNatively,
     },
   },
 };

package.json

@@ -54,6 +54,7 @@
     "eslint-config-prettier": "^8.3.0",
     "eslint-plugin-prettier": "^4.0.0",
     "jest": "^27.4.7",
+    "jest-light-runner": "^0.7.10",
     "release-plan": "^0.9.0",
     "rimraf": "^3.0.2",
     "ts-jest": "^27.1.3",

src/index.ts

@@ -1,17 +1,18 @@
-import { transformAsync, createConfigItem } from '@babel/core';
+// @ts-expect-error Type definitions don't know about createConfigItemSync
+import { transformAsync, createConfigItemSync } from '@babel/core';
 import type { VisitNodeObject, Node } from '@babel/traverse';
-import { format, Options as PrettierOptions } from 'prettier';
+import { format, type Options as PrettierOptions } from 'prettier';
 
 // @ts-expect-error We're only importing so we can create a config item, so we don't care about types
 import bts from '@babel/plugin-transform-typescript';
-const babelTsTransform = createConfigItem([
+const babelTsTransform = createConfigItemSync([
   bts,
   { allowDeclareFields: true, onlyRemoveTypeImports: true },
 ]);
 
 // @ts-expect-error We're only importing so we can create a config item, so we don't care about types
 import bsd from '@babel/plugin-syntax-decorators';
-const babelDecoratorSyntax = createConfigItem([bsd, { legacy: true }]);
+const babelDecoratorSyntax = createConfigItemSync([bsd, { version: 'legacy' }]);
 
 export async function removeTypes(code: string, prettierConfig: PrettierOptions | boolean = true) {
   // Babel collapses newlines all over the place, which messes with the formatting of almost any

test/index.test.ts

@@ -1,4 +1,4 @@
-import { removeTypes } from '../src';
+import { removeTypes } from '../src/index.ts';
 
 describe('removeTypes', () => {
   it(`preserves default exports`, async () => {

tsconfig.json

@@ -3,6 +3,7 @@
     "target": "es2020",
     "module": "es2020",
     "removeComments": true,
+    "allowImportingTsExtensions": true,
 
     "strict": true,
     "noUnusedLocals": true,