fix(typescript): fix ESM build

packages/typescript/src/customTransformers.ts

@@ -1,7 +1,6 @@
-import { BuilderProgram, CustomTransformers, Program, TypeChecker } from 'typescript';
+import type { BuilderProgram, CustomTransformers, Program, TypeChecker } from 'typescript';
 
 import type { CustomTransformerFactories, TransformerStage, TransformerFactory } from '../types';
-
 /**
  * Merges all received custom transformer definitions into a single CustomTransformers object
  */

packages/typescript/src/moduleResolution.ts

@@ -1,4 +1,4 @@
-import {
+import type {
   ModuleResolutionHost,
   ResolvedModuleFull,
   ResolvedProjectReference,

packages/typescript/src/options/plugin.ts

@@ -1,4 +1,4 @@
-import * as defaultTs from 'typescript';
+import defaultTs from 'typescript';
 
 import type { RollupTypescriptOptions, PartialCompilerOptions } from '../../types';
 import { getTsLibPath } from '../tslib';

packages/typescript/src/options/tsconfig.ts

@@ -2,12 +2,11 @@ import { readFileSync } from 'fs';
 import { dirname, resolve } from 'path';
 
 import { PluginContext } from 'rollup';
-import {
+import typescript from 'typescript';
+import type {
   Diagnostic,
   ExtendedConfigCacheEntry,
   MapLike,
-  ModuleKind,
-  ModuleResolutionKind,
   ParsedCommandLine,
   ProjectReference,
   TypeAcquisition,
@@ -28,6 +27,7 @@ import {
 } from './interfaces';
 import { normalizeCompilerOptions, makePathsAbsolute } from './normalize';
 
+const { ModuleKind, ModuleResolutionKind } = typescript;
 export interface TypeScriptConfig {
   autoSetSourceMap: boolean;
   options: CompilerOptions;

packages/typescript/src/preflight.ts

@@ -1,9 +1,10 @@
 import { PluginContext, RollupOptions } from 'rollup';
-import { ModuleKind } from 'typescript';
+import typescript from 'typescript';
 
 import { TypeScriptConfig } from './options/tsconfig';
 // import { resolveIdAsync } from './tslib';
 
+const { ModuleKind } = typescript;
 interface PreflightOptions {
   config: TypeScriptConfig;
   context: PluginContext;

packages/typescript/src/tslib.ts

@@ -1,3 +1,5 @@
+import { fileURLToPath } from 'url';
+
 import resolve, { SyncOpts } from 'resolve';
 
 // const resolveIdAsync = (file: string, opts: AsyncOpts) =>
@@ -19,7 +21,8 @@ export const getTsLibPath = () => {
   try {
     // eslint-disable-next-line no-underscore-dangle
     return resolveId(process.env.__TSLIB_TEST_PATH__ || 'tslib/tslib.es6.js', {
-      basedir: __dirname
+      // @ts-ignore import.meta.url is allowed because the Rollup plugin injects the correct module format
+      basedir: fileURLToPath(new URL('.', import.meta.url))
     });
   } catch (_) {
     return null;

packages/typescript/src/watchProgram.ts

@@ -1,6 +1,5 @@
 import { PluginContext } from 'rollup';
-import { DiagnosticCategory } from 'typescript';
-
+import typescript from 'typescript';
 import type {
   Diagnostic,
   EmitAndSemanticDiagnosticsBuilderProgram,
@@ -17,6 +16,7 @@ import { DiagnosticsHost } from './diagnostics/host';
 import { Resolver } from './moduleResolution';
 import { mergeTransformers } from './customTransformers';
 
+const { DiagnosticCategory } = typescript;
 type BuilderProgram = EmitAndSemanticDiagnosticsBuilderProgram;
 
 // @see https://github.com/microsoft/TypeScript/blob/master/src/compiler/diagnosticMessages.json

packages/typescript/test/test.mjs

@@ -0,0 +1,23 @@
+import { fileURLToPath } from 'url';
+
+import test from 'ava';
+
+import { rollup } from 'rollup';
+
+import typescript from 'current-package';
+
+import { getCode, onwarn } from '../../../util/test.js';
+
+test.beforeEach(() => process.chdir(fileURLToPath(new URL('.', import.meta.url))));
+
+test.serial('works as ESM build', async (t) => {
+  const bundle = await rollup({
+    input: 'fixtures/basic/main.ts',
+    plugins: [typescript({ tsconfig: 'fixtures/basic/tsconfig.json', target: 'es5' })],
+    onwarn
+  });
+  const code = await getCode(bundle, { format: 'es' });
+
+  t.false(code.includes('number'), code);
+  t.false(code.includes('const'), code);
+});

shared/ava.config.mjs

@@ -1,6 +1,6 @@
 export default {
   workerThreads: false,
-  extensions: ['js', 'ts'],
+  extensions: ['js', 'mjs', 'ts'],
   files: ['!**/fixtures/**', '!**/output/**', '!**/helpers/**', '!**/recipes/**', '!**/types.ts'],
   require: ['ts-node/register', 'esm']
 };