Braintree\Gateway::clientToken PHP Method

    public function clientToken()
    {
        return new ClientTokenGateway($this);
    }

 public function testGateway_VersionDefaultsToTwo()
 {
     $gateway = new Braintree\Gateway(array('environment' => 'development', 'merchantId' => 'integration_merchant_id', 'publicKey' => 'integration_public_key', 'privateKey' => 'integration_private_key'));
     $encodedClientToken = $gateway->clientToken()->generate();
     $clientToken = base64_decode($encodedClientToken);
     $version = json_decode($clientToken)->version;
     $this->assertEquals(2, $version);
 }