PHPCode for stackoverflow question

<?php
class SignUpController {
  public function __construct($validator) {
    $this->validator = $validator;
  }

  public function openUserAccount($email, $password) {
    if ( ! $this->validator->validate($email)) throw new Exception("Email is invalid");
    //do registration
    return true;
  }
}

class Validator {
  public function validate($email) {
    if (preg_match("/^[^\.]+@.+$/", $email)) return true; //this is first requirement

    //this true after requirement changed but support I forgot to made a change to this class
    //because it written by someone else and I don't know it exist
    // TODO: you can uncomment this line to make requirement met
    // if (preg_match("/.+@.+/", $email)) return true;

    return false;
  }
}

class AllTest extends PHPUnit_Framework_TestCase {

  /**
  * @expectedException Exception
  */
  public function test_openUserAccount_not_allow_period_in_email() {
    $mock = $this->getMock('Validator');
    $mock->expects($this->once())
         ->method('validate')
       ->with('my.name@example.com')
       ->will($this->returnValue(false));

    $ctrl = new SignUpController($mock);
    $ctrl->openUserAccount('my.name@example.com', 'password');
  }

  public function test_openUserAccount_return_true_with_valid_email() {
    $mock = $this->getMock('Validator');
    $mock->expects($this->once())
         ->method('validate')
       ->with('valid@example.com')
       ->will($this->returnValue(true));

    $ctrl = new SignUpController($mock);
    $this->assertSame(true, $ctrl->openUserAccount('valid@example.com', 'password'));
  }

  //There are much more test for openUserAccount that handle every edge case that might happen
  //All test continued more than 500 line that make test hard to find what missing else
  //Sometimes other developer mock class in other file, somewhere else that I don't known
  //and we're almost forgot it because it's a long time ago

  // // TODO: uncomment below test to see all test still pass
  // // after requirement changed, I add new test then all test still pass
  // // without any modification to another test
  // public function test_openUserAccount_return_true_with_period_in_email() {
  //   $mock = $this->getMock('Validator');
  //   $mock->expects($this->once())
  //        ->method('validate')
  //      ->with('my.name@example.com')
  //      ->will($this->returnValue(true));

  //   $ctrl = new SignUpController($mock);
  //   $this->assertSame(true, $ctrl->openUserAccount('my.name@example.com', 'password'));
  // }

  // I need to combine Validator test to this class to make phpunit run all test in same file
  public function test_validate_with_period_return_false() {
    $inst = new Validator();
    $this->assertSame(false, $inst->validate('with.period@example.com'));
  }

  public function test_validate_without_period_return_true() {
    $inst = new Validator();
    $this->assertSame(true, $inst->validate('withoutperiod@example.com'));
  }

  // //This is a test that support new requirement of validator
  // //even i add this test and remove test_validate_with_period_return_false
  // //how about mock of Validator in test above? how do I known where is using this class
  // //Mock don't reflect error after this method changed
  // public function test_validate_after_requirement_changed_period_must_allow() {
  //   $inst = new Validator();
  //   $this->assertSame(true, $inst->validate('with.period@example.com'));
  // }
}