Add test for microsoft#47806

tests/cases/fourslash/server/nodeNextModuleKindCaching1.ts

@@ -0,0 +1,35 @@
+/// <reference path="../fourslash.ts"/>
+
+// @Filename: tsconfig.json
+////{
+////    "compilerOptions": {
+////      "rootDir": "src",
+////      "outDir": "dist",
+////      "target": "ES2020",
+////      "module": "NodeNext",
+////      "strict": true
+////    },
+////    "include": ["src\\**\\*.ts"]
+////}
+
+// @Filename: package.json
+////{
+////    "type": "module",
+////    "private": true
+////}
+
+// @Filename: src/index.ts
+////// The line below should show a "Relative import paths need explicit file
+////// extensions..." error in VS Code, but it doesn't. The error is only picked up
+////// by `tsc` which seems to properly infer the module type.
+////import { helloWorld } from './example'
+/////**/
+////helloWorld()
+
+// @Filename: src/example.ts
+////export function helloWorld() {
+////    console.log('Hello, world!')
+////}
+
+goTo.marker();
+verify.numberOfErrorsInCurrentFile(1);