Checkout the clam-test-data repository at any directory
 $ svn co https://iua-share.upf.edu/svn/clam-test-data/trunk clam-test-data

And compile with 
 $ scons data_prefix=path/to/clam-test-data clam_prefix=/usr/local or clam_prefix=~/local

You need to install libcppunit. In Ubuntu: 
 $ sudo apt-get install libcppunit-dev