public static File getFile(String fileName) {
        String extension = fileName.substring(fileName.lastIndexOf('.') + 1);
        File toReturn = ResourceHelper.getFileResourcesByExtension(extension)
                .stream()
                .filter(file -> file.getName().equals(fileName))
                .findFirst()
                .orElse(null);
        if (toReturn == null) {
            throw new IllegalArgumentException("Failed to find file " + fileName);
        }
        return toReturn;
    }
@Test
    public void getFileNotExistingDirectory() {
        assertThatExceptionOfType(IllegalArgumentException.class).isThrownBy(() -> FileUtils.getFile(TEST_FILE, NOT_EXISTING_DIRECTORY));
    }