Any open source tool available in market for testing purpose..i want gui tool (no winbind/sssd).
I am not sure if there is a free AD version but Microsoft Active Directory implements LDAP protocol. LDAP is just a protocol that defines the methods by which directory data is accessed. LDAP also specifies how data is loaded and how data is represented. It does not specifies how data is stored. Each implementation of LDAP can be different when it comes to storing data.
Testing on OpenLDAP should be the closest thing you can get to testing against Active Directory as both implement LDAP protocol.