add unit test driver

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/math/polysat/solver.cpp

@@ -154,6 +154,11 @@ namespace polysat {
         return v;
     }
 
+    pdd solver::value(rational const& v, unsigned sz) {
+        return sz2pdd(sz).mk_val(v);
+    }
+
+
     void solver::del_var() {
         // TODO also remove v from all learned constraints.
         pvar v = m_viable.size() - 1;

src/math/polysat/solver.h

@@ -325,6 +325,11 @@ namespace polysat {
          */
         pdd var(pvar v) { return m_vars[v]; }
 
+        /**
+         * Create polynomial constant.
+         */
+        pdd value(rational const& v, unsigned sz);
+
         /**
          * Return value of v in the current model (only meaningful if check_sat() returned l_true).
          */