SimpleTest documentation for testing log-in and authentication

# Authentication documentation

This page...

- Getting through Basic HTTP authentication
- Testing cookie based authentication
- Managing browser sessions and timeouts

One of the trickiest, and yet most important, areas of testing web sites is the security. Testing these schemes is one of the core goals of the SimpleTest web tester.

## Basic HTTP authentication

If you fetch a page protected by basic authentication then rather than receiving content, you will instead get a 401 header. We can illustrate this with this test...

    class AuthenticationTest extends WebTestCase {
        function test401Header() {
            $this->get('http://www.lastcraft.com/protected/');
            $this->showHeaders();
        }
    }

This allows us to see the challenge header...

# File test

    HTTP/1.1 401 Authorization Required
    Date: Sat, 18 Sep 2004 19:25:18 GMT
    Server: Apache/1.3.29 (Unix) PHP/4.3.4
    WWW-Authenticate: Basic realm="SimpleTest basic authentication"
    Connection: close
    Content-Type: text/html; charset=iso-8859-1

1/1 test cases complete. 0 passes, 0 fails and 0 exceptions.
We are trying to get away from visual inspection though, and so SimpleTest allows to make automated assertions against the challenge. Here is a thorough test of our header...

    class AuthenticationTest extends WebTestCase {
        function test401Header() {
            $this->get('http://www.lastcraft.com/protected/');
            $this->assertAuthentication('Basic');
            $this->assertResponse(401);
            $this->assertRealm('SimpleTest basic authentication');
        }
    }

Any one of these tests would normally do on it's own depending on the amount of detail you want to see.

One theme that runs through SimpleTest is the ability to use SimpleExpectation objects wherever a simple match is not enough. If you want only an approximate match to the realm for example, you can do this...

    class AuthenticationTest extends WebTestCase {
        function test401Header() {
            $this->get('http://www.lastcraft.com/protected/');
            $this->assertRealm(new PatternExpectation('/simpletest/i'));
        }
    }

This type of test, testing HTTP responses, is not typical.

Most of the time we are not interested in testing the authentication itself, but want to get past it to test the pages underneath. As soon as the challenge has been issued we can reply with an authentication response...

    class AuthenticationTest extends WebTestCase {
        function testCanAuthenticate() {
            $this->get('http://www.lastcraft.com/protected/');
            $this->authenticate('Me', 'Secret');
            $this->assertTitle(...);
        }
    }

The username and password will now be sent with every subsequent request to that directory and subdirectories. You will have to authenticate again if you step outside the authenticated directory, but SimpleTest is smart enough to merge subdirectories into a common realm.

If you want, you can shortcut this step further by encoding the log in details straight into the URL...

    class AuthenticationTest extends WebTestCase {
        function testCanReadAuthenticatedPages() {
            $this->get('http://Me:Secret@www.lastcraft.com/protected/');
            $this->assertTitle(...);
        }
    }

If your username or password has special characters, then you will have to URL encode them or the request will not be parsed correctly. I'm afraid we leave this up to you.

A problem with encoding the login details directly in the URL is the authentication header will not be sent on subsequent requests. If you navigate with relative URLs though, the authentication information will be preserved along with the domain name.

Normally though, you use the authenticate() call. SimpleTest will then remember your login information on each request.

Only testing with basic authentication is currently supported, and this is only really secure in tandem with HTTPS connections. This is usually good enough to protect test server from prying eyes, however. Digest authentication and NTLM authentication may be added in the future if enough people request this feature.

## Cookies

Basic authentication doesn't give enough control over the user interface for web developers. More likely this functionality will be coded directly into the web architecture using cookies with complicated timeouts. We need to be able to test this too.

Starting with a simple log-in form...

    <form>
        Username:
        <input type="text" name="u" value="" /><br />
        Password:
        <input type="password" name="p" value="" /><br />
        <input type="submit" value="Log in" />
    </form>

Which looks like...

Username:
Password:

Let's suppose that in fetching this page a cookie has been set with a session ID. We are not going to fill the form in yet, just test that we are tracking the user. Here is the test...

    class LogInTest extends WebTestCase {
        function testSessionCookieSetBeforeForm() {
            $this->get('http://www.my-site.com/login.php');
            $this->assertCookie('SID');
        }
    }

All we are doing is confirming that the cookie is set. As the value is likely to be rather cryptic it's not really worth testing this with...

    class LogInTest extends WebTestCase {
        function testSessionCookieIsCorrectPattern() {
            $this->get('http://www.my-site.com/login.php');
            $this->assertCookie('SID', new PatternExpectation('/[a-f0-9]{32}/i'));
        }
    }

If you are using PHP to handle sessions for you then this test is even more useless, as we are just testing PHP itself.

The simplest test of logging in is to visually inspect the next page to see if you are really logged in. Just test the next page with WebTestCase::assertText().

The test is similar to any other form test, but we might want to confirm that we still have the same cookie after log-in as before we entered. We wouldn't want to lose track of this after all. Here is a possible test for this...

    class LogInTest extends WebTestCase {
        ...
        function testSessionCookieSameAfterLogIn() {
            $this->get('http://www.my-site.com/login.php');
            $session = $this->getCookie('SID');
            $this->setField('u', 'Me');
            $this->setField('p', 'Secret');
            $this->click('Log in');
            $this->assertText('Welcome Me');
            $this->assertCookie('SID', $session);
        }
    }

This confirms that the session identifier is maintained afer log-in and we haven't accidently reset it.

We could even attempt to hack our own system by setting arbitrary cookies to gain access...

    class LogInTest extends WebTestCase {
        ...
        function testSessionCookieSameAfterLogIn() {
            $this->get('http://www.my-site.com/login.php');
            $this->setCookie('SID', 'Some other session');
            $this->get('http://www.my-site.com/restricted.php');
            $this->assertText('Access denied');
        }
    }

Is your site protected from this attack?

## Browser sessions

If you are testing an authentication system a critical piece of behaviour is what happens when a user logs back in. We would like to simulate closing and reopening a browser...

    class LogInTest extends WebTestCase {
        ...
        function testLoseAuthenticationAfterBrowserClose() {
            $this->get('http://www.my-site.com/login.php');
            $this->setField('u', 'Me');
            $this->setField('p', 'Secret');
            $this->click('Log in');
            $this->assertText('Welcome Me');

            $this->restart();
            $this->get('http://www.my-site.com/restricted.php');
            $this->assertText('Access denied');
        }
    }

The WebTestCase::restart() method will preserve cookies that have unexpired timeouts, but throw away those that are temporary or expired. You can optionally specify the time and date that the restart happened.

Expiring cookies can be a problem. After all, if you have a cookie that expires after an hour, you don't want to stall the test for an hour while waiting for the cookie to pass it's timeout.

To push the cookies over the hour limit you can age them before you restart the session...

    class LogInTest extends WebTestCase {
        ...
        function testLoseAuthenticationAfterOneHour() {
            $this->get('http://www.my-site.com/login.php');
            $this->setField('u', 'Me');
            $this->setField('p', 'Secret');
            $this->click('Log in');
            $this->assertText('Welcome Me');

            $this->ageCookies(3600);
            $this->restart();
            $this->get('http://www.my-site.com/restricted.php');
            $this->assertText('Access denied');
        }
    }

After the restart it will appear that cookies are an hour older, and any that pass their expiry will have disappeared.
References and related information...

- SimpleTest project page on SourceForge.
- SimpleTest download page on LastCraft.
- The developer's API for SimpleTest gives full detail on the classes and assertions available.

Copyright
Marcus Baker 2006