public synchronized OutputStream open() {
        try {
            close();
            fileOutputStream = new FileOutputStream(file, true);
        } catch (FileNotFoundException e) {
            throw new RuntimeException("Unable to open output stream", e);
        }
        return fileOutputStream;
    }
@Test(expected = RuntimeException.class)
    public void requireThatExceptionIsThrowIfFileNotFound() throws IOException {
        File file = new File("mydir1");
        file.delete();
        assertTrue(file.mkdir());
        new FileLogTarget(file).open();
    }