added slightly better random(Module,Module) strategy

Author: mahrud

M2/Macaulay2/m2/genmat.m2

@@ -113,8 +113,10 @@ randomMR := opts -> (F,G) -> (
      map(F,G,new Matrix from f))
 
 random(Module, Module) := Matrix => opts -> (F,G) -> (
-    if not isFreeModule F or not isFreeModule G
+    if not isFreeModule G
     then return homomorphism random(Hom(G, F, DegreeLimit => 0), opts);
+    if not isFreeModule F
+    then return map(F, G, random(cover F, G, opts));
      R := ring F;
      if R =!= ring G then error "modules over different rings";
      if opts.MaximalRank then return (randomMR opts)(F,G);

M2/Macaulay2/tests/normal/randommod.m2

@@ -4,3 +4,8 @@ f = random(S^1, S^1/x)
 assert isWellDefined f
 assert(target f === S^1)
 assert(source f === S^1/x)
+
+f = random(S^1/x, S^1)
+assert isWellDefined f
+assert(target f === S^1/x)
+assert(source f === S^1)