String[] testFileParts = file.toURI().toURL().getPath().split(REST_TEST_PREFIX);
            if (testFileParts.length != 2) {
                throw new IllegalArgumentException("could not split " + file + " into expected parts");
            }
            File output = new File(outputDirectory.get().dir(REST_TEST_PREFIX).getAsFile(), testFileParts[1]);
            output.getParentFile().mkdirs();