Custom plugin: How to test deep configuration of Gradle Project

I write a custom Gradle plugin. Started working on integration testing and faced the following question:

My plugin applies the following logic, among other things:

repositories.maven(repository -> {

Then, while testing with Spock:

def "repositories are set up correctly"() {
    def repositories = project.repositories

    repositories.size() == 1
    repositories[0] instanceof MavenArtifactRepository
    def repoReleases = repositories[0] as MavenArtifactRepository == NAME
    repoReleases.url.toString() == URL
    // how to check that this repository is for releases only?

How do I prompt the project to show me whether it will use this repository for snapshots or not?

Or is this kind of deep testing not worth the effort?