Test Collab does support alternative authentication methods like Active Directory and LDAP.
Users added on your Test Collab instance can use these alternative methods to access the instance.
To use the feature you need to have PHP's LDAP extension installed on the hosting server.
Once the alternative authentication method has been configured you can provide LDAP / AD username for every user added on your Test Collab instance.
Even after configuring Active Directory (LDAP) you can opt to have the default authentication system as fallback.
Details on using alternative authentication methods are available on the online user guide article accessible at http://support.testcollab.com/index.php?pg=kb.page&id=98