Why does path resolution change in a multi-module project when trying to load resources in a test?

I have a file in my src/main/resources folder in a multi-module Gradle project:

modulename/src/main/resources/file

If I try to load it from my program it works just fine:

new File("modulename/src/main/resources/file").exists()

// true

but when I try to load the same file from a test, it fails:

java.io.FileNotFoundException: modulename/src/main/resources/file (The system cannot find the path specified)

I fiddled around with this and it turned out that it only finds this file if I remove the module name from the path when I'm trying to load the file in a test:

new File("modulename/src/main/resources/file").exists()

// false

new File("src/main/resources/file").exists()

// true

Why is this the case and how can I fix this? My problem is that I have an enum which contains hard-coded paths for some resources and I can't change it from my test.

There is a caveat: I can't use the getResourceAsStream method to alleviate this problem for some internal reason.