/**
  * Checks if a file has been modified
  */
 public function testHasBeenModified()
 {
     $this->copy();
     $mbox = new Mail_Mbox(Mail_MboxTest::$filecopy);
     $this->assertTrue($mbox->open());
     $this->assertFalse($mbox->hasBeenModified());
     //get a new timestamp for the change
     sleep(1);
     $mbox2 = new Mail_Mbox(Mail_MboxTest::$filecopy);
     $this->assertTrue($mbox2->open());
     $this->assertTrue($mbox2->remove(0));
     $this->assertTrue($mbox2->close());
     $this->assertTrue($mbox->hasBeenModified());
     //This methods should not allow modifying a changed file.
     $err = $mbox->remove(0);
     $this->assertType('PEAR_Error', $err);
     $this->assertEquals(MAIL_MBOX_ERROR_MODIFIED, $err->getCode());
     $err = $mbox->insert('From Test');
     $this->assertType('PEAR_Error', $err);
     $this->assertEquals(MAIL_MBOX_ERROR_MODIFIED, $err->getCode());
     $err = $mbox->update(0, 'From Test');
     $this->assertType('PEAR_Error', $err);
     $this->assertEquals(MAIL_MBOX_ERROR_MODIFIED, $err->getCode());
     $this->assertTrue($mbox->close());
 }