Added unit tests.

(cherry picked from commit bb8fcba8)

src/@dseries/firstdate.m

-function f = firstdate(o)
+function f = firstdate(o) % --*-- Unitary tests --*--
 
-% Copyright (C) 2014 Dynare Team
+% Copyright (C) 2016 Dynare Team
 %
 % This file is part of Dynare.
 %
@@ -17,4 +17,20 @@ function f = firstdate(o)
 % You should have received a copy of the GNU General Public License
 % along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
 
-f = o.dates(1);
\ No newline at end of file
+f = o.dates(1);
+
+%@test:1
+%$ try
+%$     ts = dseries(randn(10, 3),'1938Q3');
+%$     dd = ts.firstdate();
+%$     t(1) = true;
+%$ catch
+%$     t(1) = false;
+%$ end
+%$
+%$ if t(1)
+%$     t(2) = isequal(dd, dates('1938Q3'));
+%$ end
+%$
+%$ T = all(t);
+%@eof:1

src/@dseries/isnan.m

-function b = isnan(o)
+function b = isnan(o) % --*-- Unitary tests --*--
 
 % Returns an array of logicals (true/false). Element (t,i) is true iff the i-th variable at
 % period number t is not a NaN.
@@ -27,4 +27,25 @@ function b = isnan(o)
 % You should have received a copy of the GNU General Public License
 % along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
 
-b = isnan(o.data);
\ No newline at end of file
+b = isnan(o.data);
+
+%@test:1
+%$ try
+%$     data = randn(100, 10);
+%$     cnan = randi(10, 50, 1);
+%$     rnan = randi(100, 50, 1);
+%$     for i=1:50, data(rnan(i),cnan(i)) = NaN; end
+%$     inan = isnan(data);
+%$     ts = dseries(data);
+%$     dd = ts.isnan();
+%$     t(1) = true;
+%$ catch
+%$     t(1) = false;
+%$ end
+%$
+%$ if t(1)
+%$     t(2) = isequal(dd, inan);
+%$ end
+%$
+%$ T = all(t);
+%@eof:1