private void assertIsDirectoryTree(FileTree classFiles, Set<String> includes, Set<String> excludes) {
assertThat(classFiles, instanceOf(CompositeFileTree.class));
CompositeFileTree files = (CompositeFileTree) classFiles;
DefaultFileCollectionResolveContext context = new DefaultFileCollectionResolveContext();
files.resolve(context);
List<? extends FileTree> contents = context.resolveAsFileTrees();
FileTreeAdapter adapter = (FileTreeAdapter) contents.get(0);
assertThat(adapter.getTree(), instanceOf(DirectoryFileTree.class));
DirectoryFileTree directoryFileTree = (DirectoryFileTree) adapter.getTree();
assertThat(directoryFileTree.getDir(), equalTo(classesDir));