It is to be placed under "modules" subdirectory of a trunk checkout.
No additional changes to build files are necessary, it'll be picked up
automatically.
+
+To include "rostests" in your build folder:
+1. Copy the rostests folder into the reactos\modules folder, or
+2. Link reactos/modules/rostests to rostests
+
+# For Windows users
+
+ cd %%_ROSSOURCEDIR%%\reactos\modules
+ mklink /j rostests %%_ROSSOURCEDIR%%\rostests
+
+# For UNIX users
+
+ cd \$$_ROSSOURCEDIR/reactos/modules
+ ln -s \$$_ROSSOURCEDIR/rostests rostests