How to execute all tests in PHPUnit?

I'm trying run all tests from my testsuite, but PHPUnit not found the tests when I run command phpunit. I config testsuite in phpunit.xml.

phpunit.xml

<?xml version="1.0" encoding="UTF-8" ?>
<phpunit backupGlobals="true"
         backupStaticAttributes="false"
         bootstrap="./bootstrap.php"
         cacheTokens="false"
         colors="true"
         convertErrorsToExceptions="true"
         convertNoticesToExceptions="true"
         convertWarningsToExceptions="true"
         forceCoversAnnotation="false"
         mapTestClassNameToCoveredClassName="false"
         processIsolation="false"
         stopOnError="false"
         stopOnFailure="false"
         stopOnIncomplete="false"
         stopOnSkipped="false"
         strict="false"
         verbose="true">
    <testsuites>
        <testsuite name="All Tests">
            <directory suffix="*.php">.</directory>
        </testsuite>
    </testsuites>
</phpunit>

bootstrap.php

<?php

error_reporting(E_ALL | E_STRICT);
date_default_timezone_set('America/Sao_Paulo');
require_once(dirname(__FILE__) . '/WebTestCase.php');

WebTestCase.php

<?php

define('TEST_BASE_URL', 'http://localhost:8080');

class WebTestCase extends PHPUnit_Extensions_SeleniumTestCase
{

    protected function setUp() {
        $this->setBrowser('*firefox');
        $this->setBrowserUrl(TEST_BASE_URL);
        $this->setHost('localhost');
        $this->setTimeOut(30);
    }
}

TestPage.php

class TestPage extends WebTestCase
{

    public function testTitle()
    {
        $this->open("/");
        $title = $this->getTitle();
        $this->assertEquals('Home', $title);
    }
}

If I run phpunit passing file test, as phpunit TestPage.php, is ok.