Issue 2105 more detailed error

CHANGELOG.md

@@ -8,7 +8,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 Please see [CONTRIBUTING.md](./CONTRIBUTING.md) on how to contribute to Cucumber.
 
 ## [Unreleased]
-
+- Change the error message emitted when trying to import a CommonJS module with the --import directive or require an ES module with the --require directive to one less cryptic than that emitted by NodeJS ([2264](https://github.com/cucumber/cucumber-js/pull/2264))
 ## [9.0.1] - 2023-03-15
 ### Fixed
 - Ensure feature paths are properly deduplicated ([#2258](https://github.com/cucumber/cucumber-js/pull/2258))

features/esm_require_import_error.feature

@@ -0,0 +1,47 @@
+@dev
+Feature: ES and CommonJS Error disabiguation
+
+  Import must be used for ES modules, Require for
+  CommonJS modules, but when developers cross these up
+  cucumber-js needs to throw an understandable error.
+
+  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$/, function() {});
+      """
+    When I run cucumber-js with `--require features/**/*.js`
+    Then it fails
+    And the error output contains the text:
+      """
+        Error: Cucumber expected a CommonJS module 
+      """
+
+  Scenario: CommonJS module invoked with --import
+    Given a file named "features/a.feature" with:
+      """
+      Feature:
+        Scenario: one
+          Given a step passes
+      """
+    And a file named "features/step_definitions/cucumber_steps.mjs" with:
+      """
+      const {Given} = require('@cucumber/cucumber')
+
+      Given(/^a step passes$/, function() {});
+      """
+    When I run cucumber-js with `--import features/**/*.mjs`
+    Then it fails
+    And the error output contains the text:
+      """
+        Error: Cucumber expected an ES module
+      """
+

src/api/support.ts

@@ -6,6 +6,19 @@ import { pathToFileURL } from 'url'
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const { importer } = require('../importer')
 
+function tryRequire(path: string) {
+  try {
+    return require(path)
+  } catch (error) {
+    if (error.message === 'Cannot use import statement outside a module') {
+      throw new 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`)
+    } else {
+      throw error
+    }
+  }
+}
+
 export async function getSupportCodeLibrary({
   cwd,
   newId,
@@ -24,10 +37,13 @@ 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/importer.js

@@ -7,7 +7,16 @@
  * @return {Promise<any>} Promise that resolves to the loaded module
  */
 async function importer(descriptor) {
-  return await import(descriptor)
+  return await import(descriptor).catch((error) => {
+    if (error.message.includes('require is not defined in ES module scope')) {
+      throw new Error(
+        `Cucumber expected an ES module at '${descriptor}' but found a CommonJS module. 
+         Either change the file to ES syntax or use the --require directive instead of --import`
+      )
+    } else {
+      throw error
+    }
+  })
 }
 
 module.exports = { importer }