Testing mails in Laravel 4 is a bit of a weak spot. You can say Mail::shouldReceive('send')->once()... but specifying everything the method should receive in terms of arguments as well as asserting that the closure sets the recipient and subject correctly is tedious at best. This SO answer shows an example of how to unit test a mail being sent.

There is a better way, as long as you're doing functional testing - that is, extending the TestCase that comes with Laravel and doing $this->call(...) stuff. We mock one layer deeper, the SwiftMailer service, and gain access to more rich information.

First of all, we swap the swiftmailer instance on the IoC container.

$mock = Mockery::mock('Swift_Mailer');
$this->app->make('mailer')->setSwiftMailer($mock);

Second, we define its expectations, and use Mockery's andReturnUsing to run assertions on the method call.

$mock->shouldReceive('send')->once()
  ->andReturnUsing(function($msg) {
    // assert stuff here
  });

$msg above is an instance of Swift_Message, a class which API is buried deep within the SwiftMailer class hierarchy, but I'll show the most important ones here.

$this->assertEquals('My subject', $msg->getSubject());
$this->assertEquals('foo@bar.com', $msg->getTo());
$this->assertContains('Some string', $msg->getBody());

If you're sending an email that is both HTML and plain text, you may want to get both the regular HTML body as well as the plain text one.

$htmlBody = $msg->getBody();
$children = $msg->getChildren();
$plainBody = $children[0]->getBody();

This should allow you to write shorter, more accurate and realistic tests.