fix(esm api): warn on missing module.register

Author: privatenumber

src/esm/api/register.ts

@@ -15,6 +15,10 @@ export type InitializationOptions = {
 export const register = (
 	options?: Options,
 ) => {
+	if (!module.register) {
+		throw new Error(`This version of Node.js (${process.version}) does not support module.register(). Please upgrade to Node v18.9 or v20.6 and above.`);
+	}
+
 	const { sourceMapsEnabled } = process;
 	process.setSourceMapsEnabled(true);
 

tests/index.ts

@@ -14,10 +14,7 @@ import { nodeVersions } from './utils/node-versions';
 				await runTestSuite(import('./specs/cli'), node);
 				await runTestSuite(import('./specs/watch'), node);
 				await runTestSuite(import('./specs/loaders'), node);
-				await runTestSuite(
-					import('./specs/smoke'),
-					node,
-				);
+				await runTestSuite(import('./specs/smoke'), node);
 			});
 		}
 	});

tests/specs/api.ts

@@ -386,6 +386,32 @@ export default testSuite(({ describe }, node: NodeApis) => {
 						expect(stdout).toBe('file.ts\nfoo.ts\nfoo');
 					});
 				});
+			} else {
+				test('no module.register error', async () => {
+					await using fixture = await createFixture({
+						'package.json': JSON.stringify({ type: 'module' }),
+						'register.mjs': `
+						import { register } from ${JSON.stringify(tsxEsmApiPath)};
+
+						{
+							const unregister = register();
+
+							const { message } = await import('./file?2');
+							console.log(message);
+
+							await unregister();
+						}
+						`,
+						...tsFiles,
+					});
+
+					const { stderr } = await execaNode(fixture.getPath('register.mjs'), [], {
+						nodePath: node.path,
+						nodeOptions: [],
+						reject: false,
+					});
+					expect(stderr).toMatch(`This version of Node.js (v${node.version}) does not support module.register(). Please upgrade to Node v18.9 or v20.6 and above.`);
+				});
 			}
 		});
 	});