public static void writeTestClassesLogToDisk() {
        if (Files.isDirectory(TEST_LOG_DIR)) {
            THREAD_ID_TO_LOG_MAP.forEach((threadId, logLines) -> {
                final String filename = "worker-"
                        + DbTestUtil.getGradleWorker()
                        + "_thread-"
                        + threadId
                        + ".log";
                final Path logFilePath = TEST_LOG_DIR.resolve(filename);
                try {
                    LOGGER.info("Writing test classes log to file {}", logFilePath);
                    Files.write(
                            logFilePath,
                            logLines,
                            new StandardOpenOption[]{
                                    StandardOpenOption.CREATE,
                                    StandardOpenOption.APPEND});
                } catch (IOException e) {
                    throw new RuntimeException(LogUtil.message("Error writing file {}: {}",
                            logFilePath.toAbsolutePath(), e.getMessage()), e);
                }
            });
        }
    }
Writes one file per gradle worker and thread containing all the test classes and methods
stroom-test-common/src/main/java/stroom/test/common/util/TestClassLogger.java