fix: try require first for custom formatters so transpiled ones work

CHANGELOG.md

@@ -10,6 +10,7 @@ Please see [CONTRIBUTING.md](https://github.com/cucumber/cucumber/blob/master/CO
 ## [Unreleased]
 ### Fixed
 - Allow `file://` URLs to be used as formatter/snippet paths in options ([#1963](https://github.com/cucumber/cucumber-js/pull/1963) [#1920](https://github.com/cucumber/cucumber-js/issues/1920))
+- Allow custom formatters to rely on `--require-module` transpilers ([#1985](https://github.com/cucumber/cucumber-js/pull/1985))
 
 ### Changed
 - Emit a warning when using a Node.js version that's untested with Cucumber ([#1959](https://github.com/cucumber/cucumber-js/pull/1959))

features/custom_formatter.feature

@@ -139,6 +139,7 @@ Feature: custom formatter
     Then it passes
     Examples:
       | EXT  | IMPORT_STATEMENT                                  | EXPORT_STATEMENT                  |
+      | .ts  | import {Formatter} from '@cucumber/cucumber'      | export default CustomFormatter    |
       | .mjs | import {Formatter} from '@cucumber/cucumber'      | export default CustomFormatter    |
       | .js  | const {Formatter} = require('@cucumber/cucumber') | module.exports = CustomFormatter  |
       | .js  | const {Formatter} = require('@cucumber/cucumber') | exports.default = CustomFormatter |

src/formatter/builder.ts

@@ -13,7 +13,7 @@ import { EventEmitter } from 'events'
 import EventDataCollector from './helpers/event_data_collector'
 import { Writable as WritableStream } from 'stream'
 import { SnippetInterface } from './step_definition_snippet_builder/snippet_syntax'
-import { pathToFileURL } from 'url'
+import { fileURLToPath, pathToFileURL } from 'url'
 import Formatters from './helpers/formatters'
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const { importer } = require('../importer')
@@ -97,9 +97,13 @@ const FormatterBuilder = {
     descriptor: string,
     cwd: string
   ) {
-    let CustomClass = descriptor.startsWith(`.`)
-      ? await importer(pathToFileURL(path.resolve(cwd, descriptor)))
-      : await importer(descriptor)
+    let normalised: URL | string = descriptor
+    if (descriptor.startsWith('.')) {
+      normalised = pathToFileURL(path.resolve(cwd, descriptor))
+    } else if (descriptor.startsWith('file://')) {
+      normalised = new URL(descriptor)
+    }
+    let CustomClass = await FormatterBuilder.loadFile(normalised)
     CustomClass = FormatterBuilder.resolveConstructor(CustomClass)
     if (doesHaveValue(CustomClass)) {
       return CustomClass
@@ -110,6 +114,23 @@ const FormatterBuilder = {
     }
   },
 
+  async loadFile(urlOrName: URL | string) {
+    let result
+    try {
+      // eslint-disable-next-line @typescript-eslint/no-var-requires
+      result = require(typeof urlOrName === 'string'
+        ? urlOrName
+        : fileURLToPath(urlOrName))
+    } catch (error) {
+      if (error.code === 'ERR_REQUIRE_ESM') {
+        result = await importer(urlOrName)
+      } else {
+        throw error
+      }
+    }
+    return result
+  },
+
   resolveConstructor(ImportedCode: any) {
     if (doesNotHaveValue(ImportedCode)) {
       return null
@@ -121,11 +142,6 @@ const FormatterBuilder = {
       typeof ImportedCode.default === 'function'
     ) {
       return ImportedCode.default
-    } else if (
-      typeof ImportedCode.default === 'object' &&
-      typeof ImportedCode.default.default === 'function'
-    ) {
-      return ImportedCode.default.default
     }
     return null
   },

src/formatter/builder_spec.ts

@@ -4,46 +4,36 @@ import { pathToFileURL } from 'url'
 import path from 'path'
 
 describe('custom class loading', () => {
-  it('should handle a file:// url', async () => {
-    const fileUrl = pathToFileURL(
-      path.resolve(__dirname, './fixtures/module_dot_exports.cjs')
-    ).toString()
-    const CustomClass = await FormatterBuilder.loadCustomClass(
-      'formatter',
-      fileUrl,
-      __dirname
-    )
-
-    expect(typeof CustomClass).to.eq('function')
-  })
-
-  it('should handle cjs module.exports', async () => {
-    const CustomClass = await FormatterBuilder.loadCustomClass(
-      'formatter',
-      './fixtures/module_dot_exports.cjs',
-      __dirname
-    )
-
-    expect(typeof CustomClass).to.eq('function')
-  })
-
-  it('should handle cjs exports.default', async () => {
-    const CustomClass = await FormatterBuilder.loadCustomClass(
-      'formatter',
-      './fixtures/exports_dot_default.cjs',
-      __dirname
-    )
-
-    expect(typeof CustomClass).to.eq('function')
-  })
-
-  it('should handle esm default export', async () => {
-    const CustomClass = await FormatterBuilder.loadCustomClass(
-      'formatter',
-      './fixtures/esm.mjs',
-      __dirname
-    )
-
-    expect(typeof CustomClass).to.eq('function')
+  const varieties = [
+    'esm.mjs',
+    'exports_dot_default.cjs',
+    'module_dot_exports.cjs',
+    'typescript.ts',
+  ]
+  varieties.forEach((filename) => {
+    describe(filename, () => {
+      it('should handle a relative path', async () => {
+        const CustomClass = await FormatterBuilder.loadCustomClass(
+          'formatter',
+          `./fixtures/${filename}`,
+          __dirname
+        )
+
+        expect(typeof CustomClass).to.eq('function')
+      })
+
+      it('should handle a file:// url', async () => {
+        const fileUrl = pathToFileURL(
+          path.resolve(__dirname, `./fixtures/${filename}`)
+        ).toString()
+        const CustomClass = await FormatterBuilder.loadCustomClass(
+          'formatter',
+          fileUrl,
+          __dirname
+        )
+
+        expect(typeof CustomClass).to.eq('function')
+      })
+    })
   })
 })

src/formatter/fixtures/typescript.ts

@@ -0,0 +1 @@
+export default class Formatter {}