diff -r fdc2c6fb7a24 -r 9891c9fac37e progs/knight1_sol.scala
--- a/progs/knight1_sol.scala	Tue Nov 15 23:08:09 2016 +0000
+++ b/progs/knight1_sol.scala	Wed Nov 16 14:37:18 2016 +0000
@@ -27,9 +27,12 @@
 def legal_moves(dim: Int, path: Path, x: Pos): List[Pos] = 
   moves(x).filter(is_legal(dim, path))
 
-legal_moves(8, Nil, (2,2))
-legal_moves(8, Nil, (7,7))
-
+assert(legal_moves(8, Nil, (2,2)) == 
+  List((3,4), (4,3), (4,1), (3,0), (1,0), (0,1), (0,3), (1,4)))
+assert(legal_moves(8, Nil, (7,7)) == List((6,5), (5,6)))
+assert(legal_moves(8, List((4,1), (1,0)), (2,2)) == 
+  List((3,4), (4,3), (3,0), (0,1), (0,3), (1,4)))
+assert(legal_moves(8, List((6,6)), (7,7)) == List((6,5), (5,6)))
 
 def count_tours(dim: Int, path: Path): Int = {
   if (path.length == dim * dim) 1