feat: allow to use TypeScript in the config file

packages/server/lib/configFiles.ts

@@ -0,0 +1 @@
+export const CYPRESS_CONFIG_FILES = ['cypress.json', 'cypress.config.js', 'cypress.config.ts']

packages/server/lib/plugins/child/run_plugins.js

@@ -7,11 +7,11 @@ const Promise = require('bluebird')
 const preprocessor = require('./preprocessor')
 const devServer = require('./dev-server')
 const resolve = require('../../util/resolve')
+const tsNodeUtil = require('../../util/ts_node')
 const browserLaunch = require('./browser_launch')
 const task = require('./task')
 const util = require('../util')
 const validateEvent = require('./validate_event')
-const tsNodeUtil = require('./ts_node')
 
 let registeredEventsById = {}
 let registeredEventsByName = {}

packages/server/lib/util/require_async_child.js

@@ -1,13 +1,16 @@
 require('graceful-fs').gracefulify(require('fs'))
 const stripAnsi = require('strip-ansi')
 const debug = require('debug')('cypress:server:require_async:child')
+const tsNodeUtil = require('./ts_node')
 const util = require('../plugins/util')
 const ipc = util.wrapIpc(process)
 
 require('./suppress_warnings').suppress()
 
 const { file, projectRoot } = require('minimist')(process.argv.slice(2))
 
+let tsRegistered = false
+
 run(ipc, file, projectRoot)
 
 /**
@@ -24,6 +27,14 @@ function run (ipc, requiredFile, projectRoot) {
     throw new Error('Unexpected: projectRoot should be a string')
   }
 
+  if (!tsRegistered) {
+    debug('register typescript for required file')
+    tsNodeUtil.register(projectRoot, requiredFile)
+
+    // ensure typescript is only registered once
+    tsRegistered = true
+  }
+
   process.on('uncaughtException', (err) => {
     debug('uncaught exception:', util.serializeError(err))
     ipc.send('error', util.serializeError(err))

packages/server/lib/plugins/child/ts_node.js → packages/server/lib/util/ts_node.js

@@ -1,30 +1,33 @@
 const debug = require('debug')('cypress:server:ts-node')
 const path = require('path')
 const tsnode = require('ts-node')
-const resolve = require('../../util/resolve')
+const resolve = require('./resolve')
 
-const getTsNodeOptions = (tsPath, pluginsFile) => {
+const getTsNodeOptions = (tsPath, registeredFile) => {
   return {
     compiler: tsPath, // use the user's installed typescript
     compilerOptions: {
       module: 'CommonJS',
     },
     // resolves tsconfig.json starting from the plugins directory
     // instead of the cwd (the project root)
-    dir: path.dirname(pluginsFile),
+    dir: path.dirname(registeredFile),
     transpileOnly: true, // transpile only (no type-check) for speed
   }
 }
 
-const register = (projectRoot, pluginsFile) => {
+const register = (projectRoot, registeredFile) => {
   try {
+    debug('projectRoot path: %s', projectRoot)
+    debug('registeredFile: %s', registeredFile)
     const tsPath = resolve.typescript(projectRoot)
 
     if (!tsPath) return
 
-    const tsOptions = getTsNodeOptions(tsPath, pluginsFile)
-
     debug('typescript path: %s', tsPath)
+
+    const tsOptions = getTsNodeOptions(tsPath, registeredFile)
+
     debug('registering project TS with options %o', tsOptions)
 
     require('tsconfig-paths/register')

packages/server/test/e2e/3_config_spec.js

@@ -54,4 +54,11 @@ describe('e2e config', () => {
       configFile: 'cypress.config.custom.js',
     })
   })
+
+  it('supports custom configFile in TypeScript', function () {
+    return e2e.exec(this, {
+      project: Fixtures.projectPath('config-with-custom-file-ts'),
+      configFile: 'cypress.config.custom.ts',
+    })
+  })
 })

packages/server/test/support/fixtures/projects/config-with-custom-file-ts/cypress.config.custom.ts

@@ -0,0 +1,9 @@
+const config: Record<string, any> = {
+  pageLoadTimeout: 10000,
+  e2e: {
+    defaultCommandTimeout: 500,
+    videoCompression: 20,
+  },
+}
+
+export default config

packages/server/test/support/fixtures/projects/config-with-custom-file-ts/cypress/integration/app_spec.js

@@ -0,0 +1,8 @@
+it('overrides config', () => {
+  // overrides come from plugins
+  expect(Cypress.config('defaultCommandTimeout')).to.eq(500)
+  expect(Cypress.config('videoCompression')).to.eq(20)
+
+  // overrides come from CLI
+  expect(Cypress.config('pageLoadTimeout')).to.eq(10000)
+})

packages/server/test/unit/plugins/child/run_plugins_spec.js

@@ -10,7 +10,7 @@ const util = require(`${root}../../lib/plugins/util`)
 const resolve = require(`${root}../../lib/util/resolve`)
 const browserUtils = require(`${root}../../lib/browsers/utils`)
 const Fixtures = require(`${root}../../test/support/helpers/fixtures`)
-const tsNodeUtil = require(`${root}../../lib/plugins/child/ts_node`)
+const tsNodeUtil = require(`${root}../../lib/util/ts_node`)
 
 const runPlugins = require(`${root}../../lib/plugins/child/run_plugins`)
 

packages/server/test/unit/plugins/child/ts_node_spec.js

@@ -4,9 +4,9 @@ const tsnode = require('ts-node')
 
 const resolve = require(`${root}../../lib/util/resolve`)
 
-const tsNodeUtil = require(`${root}../../lib/plugins/child/ts_node`)
+const tsNodeUtil = require(`${root}../../lib/util/ts_node`)
 
-describe('lib/plugins/child/ts_node', () => {
+describe('lib/util/ts_node', () => {
   beforeEach(() => {
     sinon.stub(tsnode, 'register')
     sinon.stub(resolve, 'typescript').returns('/path/to/typescript.js')