Initialize variable updated subsequently in a script.

tests/runalltests.m

@@ -15,6 +15,9 @@ function runalltests()
 % You should have received a copy of the GNU General Public License
 % along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
 
+dseries_src_root = []; % Initialize path as an array to be updated
+                       % when calling initialize_dseries_toolbox() script.
+
 opath = path();
 
 system('rm -f failed');