Include a less cryptic error message when trying to require an ES module (#2264)

Author: michael-lloyd-morris

CHANGELOG.md

@@ -8,8 +8,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 Please see [CONTRIBUTING.md](./CONTRIBUTING.md) on how to contribute to Cucumber.
 
 ## [Unreleased]
+
 ### Added
 - Formatters create sub-directory automatically instead of failing ([#2266](https://github.com/cucumber/cucumber-js/pull/2266))
+- Include a less cryptic error message when trying to `require` an ES module ([#2264](https://github.com/cucumber/cucumber-js/pull/2264))
 
 ### Changed
 - Change hashes type from `any` to `Record<string, string>` in `DataTable` ([#2270](https://github.com/cucumber/cucumber-js/pull/2270))

features/esm.feature

@@ -82,3 +82,23 @@ Feature: ES modules support
     When I run cucumber-js
     Then it runs 2 scenarios
     And it passes
+
+  Scenario: ES module invoked with --require
+    Given a file named "features/a.feature" with:
+      """
+      Feature:
+        Scenario: one
+          Given a step passes
+      """
+    And a file named "features/step_definitions/cucumber_steps.js" with:
+      """
+      import {Given} from '@cucumber/cucumber'
+
+      Given(/^a step passes$/, function() {});
+      """
+    When I run cucumber-js with `--require features/**/*.js`
+    Then it fails
+    And the error output contains the text:
+      """
+        Error: Cucumber expected a CommonJS module 
+      """

src/api/support.ts

@@ -2,6 +2,7 @@ import { IdGenerator } from '@cucumber/messages'
 import { ISupportCodeLibrary } from '../support_code_library_builder/types'
 import supportCodeLibraryBuilder from '../support_code_library_builder'
 import { pathToFileURL } from 'url'
+import tryRequire from '../try_require'
 
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const { importer } = require('../importer')
@@ -24,10 +25,13 @@ export async function getSupportCodeLibrary({
     requirePaths,
     importPaths,
   })
-  requireModules.map((module) => require(module))
-  requirePaths.map((path) => require(path))
+
+  requireModules.map((module) => tryRequire(module))
+  requirePaths.map((path) => tryRequire(path))
+
   for (const path of importPaths) {
     await importer(pathToFileURL(path))
   }
+
   return supportCodeLibraryBuilder.finalize()
 }

src/runtime/parallel/worker.ts

@@ -14,6 +14,7 @@ import {
   IWorkerCommandInitialize,
   IWorkerCommandRun,
 } from './command_types'
+import tryRequire from '../../try_require'
 
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const { importer } = require('../../importer')
@@ -74,8 +75,8 @@ export default class Worker {
       requirePaths,
       importPaths,
     })
-    requireModules.map((module) => require(module))
-    requirePaths.map((module) => require(module))
+    requireModules.map((module) => tryRequire(module))
+    requirePaths.map((module) => tryRequire(module))
     for (const path of importPaths) {
       await importer(pathToFileURL(path))
     }

src/try_require.ts

@@ -0,0 +1,22 @@
+/**
+ * Provides a try guarded require call that will throw a more detailed error when
+ * the ERR_REQUIRE_ESM error code is encountered.
+ *
+ * @param {string} path File path to require from.
+ */
+export default function tryRequire(path: string) {
+  try {
+    return require(path)
+  } catch (error) {
+    if (error.code === 'ERR_REQUIRE_ESM') {
+      throw Error(
+        `Cucumber expected a CommonJS module at '${path}' but found an ES module.
+      Either change the file to CommonJS syntax or use the --import directive instead of --require.
+      
+      Original error message: ${error.message}`
+      )
+    } else {
+      throw error
+    }
+  }
+}