There are many applications, tests, and extra subsystems in the ReactOS SVN. Most are not installed into the bootcd by default and requires a few easy steps. In the reactos\modules (reactos/modules) are two files, empty.rbuild and directory.rbuild. If the build environment does not detect anything in the modules folder, it will automatically revert to the empty.rbuild. If there are folders, the BE will use directory.rbuild to figure out what to do. Within it, there are several <directory name ="x">. The names are of various folders within the SVN and signify the folders that can be built into ReactOS as modules.
In your local repository, copy in the folder that you want to build in. So if you want to include the rostests, put the rostests folder into modules. Then enter make bootcd to build them in. If they are not picked up, delete the makefile.auto file and retry.