Fix cannot find module (#6554)

* Add test and fixture

* Fix cannot find module issue

createRequire expects a path to a filename (or URL). When using cwd() it
assumes the last directory is a filename and the require will be based
upon the wrong directory (1 level up).

.changeset/tasty-steaks-prove.md

@@ -0,0 +1,5 @@
+---
+'@graphql-codegen/plugin-helpers': patch
+---
+
+Fix module not found bug in resolveExternalModuleAndFn

packages/utils/plugins-helpers/src/resolve-external-module-and-fn.ts

@@ -18,7 +18,9 @@ export function resolveExternalModuleAndFn(pointer: any): any {
   if (moduleName === 'change-case-all') {
     loadedModule = changeCaseAll;
   } else {
-    const cwdRequire = createRequire(cwd());
+    // we have to use a path to a filename here (it does not need to exist.)
+    // https://github.com/dotansimha/graphql-code-generator/issues/6553
+    const cwdRequire = createRequire(cwd() + '/index.js');
     loadedModule = cwdRequire(moduleName);
 
     if (!(functionName in loadedModule) && typeof loadedModule !== 'function') {

packages/utils/plugins-helpers/tests/fixtures/externalModuleFn.js

@@ -0,0 +1 @@
+exports.test = 'foobar';

packages/utils/plugins-helpers/tests/resolve-external-module-and-fn.spec.ts

@@ -0,0 +1,11 @@
+import path from 'path';
+import { resolveExternalModuleAndFn } from '../src/resolve-external-module-and-fn';
+
+describe.only('resolveExternalModuleAndFn', () => {
+  describe('Issues', () => {
+    it('#6553 - Cannot find module', () => {
+      const relativePathToSelf = path.relative(process.cwd(), path.join(__dirname, './fixtures/externalModuleFn.js'));
+      expect(resolveExternalModuleAndFn('./' + relativePathToSelf + '#test')).toBe('foobar');
+    });
+  });
+});