Asserts correct token replacement for the given trigger and account.
$trigger: A trigger like 'user_login'.
$account: The user account which triggered the action.
$email_depth: Number of emails to scan, starting with most recent.
function assertSystemEmailTokenReplacement($trigger, $account, $email_depth = 1) {
$this
->verboseEmail($email_depth);
$expected = $this
->generateTokenExpandedComparison($trigger, $account);
$this
->assertMailString('subject', $expected, $email_depth);
$this
->assertMailString('body', $expected, $email_depth);
$this
->assertMail('to', $account->mail, 'Mail sent to correct destination');
}