simple if test without else

unveils many a bug that is now fixed

lib/mom/if_statement.rb

@@ -8,18 +8,26 @@ module Mom
       @condition = cond
       @if_true = if_true
       @if_false = if_false
+      raise if_true.class unless if_true.is_a? Statement
     end
 
-    def flatten
-      head = hoisted.flatten
+    def flatten(options = {})
       true_label = Label.new( "true_label_#{object_id}")
       false_label = Label.new( "false_label_#{object_id}")
       merge_label = Label.new( "merge_label_#{object_id}")
-      head.append condition.flatten( true_label: true_label , false_label: false_label)
+      first = condition.flatten( true_label: true_label , false_label: false_label)
+      if hoisted
+        head = hoisted.flatten
+        head.append first
+      else
+        head = first
+      end
       head.append true_label
       head.append if_true.flatten( merge_label: merge_label)
-      head.append false_label
-      head.append if_false.flatten( merge_label: merge_label)
+      if( if_false)
+        head.append false_label
+        head.append if_false.flatten( merge_label: merge_label)
+      end
       head.append merge_label
       head
     end