public static File createUniqueFile(String prefix) {
        return new File(tempFolder(), prefix + "-" + UUID.randomUUID());
    }
@Test
    public void shouldCreateUniqueFilesParentDirectoryIfDoesNotExist() throws IOException {
        String newTmpDir = original.getProperty("java.io.tmpdir") + "/" + UUID.randomUUID();
        System.setProperty("java.io.tmpdir", newTmpDir);
        File file = files.createUniqueFile("foo");
        assertThat(file.getParentFile().exists(), is(true));
    }