Can't access module from test file

So if I have src/Demo.res and test/Demo.test.res everything is fine if I don’t need to access Demo.res. But if I need to access a function in Demo.res in the test, Demo.test.res won’t compile and I get a module or file can’t be found error.

To make things more interesting, if I add “namespace”: true to rescript.json then Demo.test.res compiles and everything works. So why doesn’t it work if namespace is not set? The files in the lib folder end up being Demo-MyApp.xxx and Demo.test-Myapp.xxx. Why does setting namespace to true make everything okay?