public function testGenerateAge()
 {
     for ($i = 0; $i < 10000; $i++) {
         $ts = OAuth2Util::generateAge(time() - 1);
         $this->assertTrue(is_int($ts));
         $this->assertGreaterThanOrEqual(1, $ts);
         $this->assertGreaterThanOrEqual($ts, 2);
     }
 }