Add warning for ts-node/esm usage

lib/codecept.js

@@ -19,7 +19,7 @@ import ActorFactory from './actor.js'
 import output from './output.js'
 import { emptyFolder } from './utils.js'
 import { initCodeceptGlobals } from './globals.js'
-import { validateTypeScriptSetup } from './utils/loaderCheck.js'
+import { validateTypeScriptSetup, getTSNodeESMWarning } from './utils/loaderCheck.js'
 import recorder from './recorder.js'
 
 import storeListener from './listener/store.js'
@@ -270,6 +270,12 @@ class Codecept {
       process.exit(1)
     }
 
+    // Show warning if ts-node/esm is being used
+    const tsWarning = getTSNodeESMWarning(this.requiringModules || [])
+    if (tsWarning) {
+      output.print(output.colors.yellow(tsWarning))
+    }
+
     // Ensure translations are loaded for Gherkin features
     try {
       const { loadTranslations } = await import('./mocha/gherkin.js')

lib/utils/loaderCheck.js

@@ -106,6 +106,26 @@ Note: TypeScript config files (codecept.conf.ts) and helpers are automatically
 `
 }
 
+/**
+ * Get warning message if ts-node/esm is being used
+ * @param {string[]} requiredModules - Array of required modules from config
+ * @returns {string|null} Warning message or null
+ */
+export function getTSNodeESMWarning(requiredModules = []) {
+  if (!requiredModules.includes('ts-node/esm')) {
+    return null
+  }
+
+  return `
+⚠️  Warning: ts-node/esm with "module": "esnext" requires explicit file extensions in all imports.
+
+This is a known limitation. Use tsx/cjs instead to write imports without extensions.
+
+📚 Documentation: https://codecept.io/typescript
+
+`
+}
+
 /**
  * Check if user is trying to run TypeScript tests without proper loader
  * @param {string[]} testFiles - Array of test file paths