add unit tests for State class

.gitignore

@@ -1,3 +1,4 @@
 /.rscons*
 /build/
 /peg-puzzle
+/peg-puzzle-test

Rsconscript

@@ -3,8 +3,13 @@ configure do
 end
 
 build do
-  Environment.new do |env|
+  main_env = Environment.new do |env|
     env["D_IMPORT_PATH"] << "src"
-    env.Program("peg-puzzle", glob("src/**/*.d"))
+    env["sources"] = glob("src/**/*.d")
+    env.Program("peg-puzzle", "${sources}")
+  end
+  test_env = main_env.clone do |env|
+    env["DFLAGS"] += %w[-g -funittest]
+    env.Program("peg-puzzle-test", "${sources}")
   end
 end

src/state.d

@@ -33,4 +33,26 @@ class State
     {
         return m_pegs[peg_index(row, col)];
     }
+
+    unittest
+    {
+        State s = new State(5);
+        assert(s.valid_position(0, 0));
+        assert(s.valid_position(4, 0));
+        assert(s.valid_position(4, 4));
+        assert(s.valid_position(2, 2));
+        assert(s.valid_position(3, 1));
+        assert(!s.valid_position(0, 1));
+        assert(!s.valid_position(0, -1));
+        assert(!s.valid_position(5, 0));
+        assert(!s.valid_position(5, 4));
+        assert(!s.valid_position(4, 5));
+        assert(!s.valid_position(2, 3));
+        assert(!s.valid_position(0, 4));
+
+        assert(s.peg_present(1, 0));
+        assert(s.peg_present(1, 1));
+        assert(s.peg_present(4, 4));
+        assert(!s.peg_present(0, 0));
+    }
 }