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
+    def flatten(options = {})
-      head = hoisted.flatten
       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
+      if( if_false)
-      head.append if_false.flatten( merge_label: merge_label)
+        head.append false_label
+        head.append if_false.flatten( merge_label: merge_label)
+      end
       head.append merge_label
       head
     end

lib/vool/statements/if_statement.rb

@@ -14,7 +14,7 @@ module Vool
 
     def to_mom( method )
       if_true =   @if_true.to_mom( method )
-      if_false =  @if_false.to_mom( method )
+      if_false =  @if_false ? @if_false.to_mom( method ) : nil
       condition , hoisted  = hoist_condition( method )
       cond = Mom::TruthCheck.new(condition.to_mom(method))
       check = Mom::IfStatement.new(  cond , if_true , if_false )
@@ -25,7 +25,7 @@ module Vool
 
     def collect(arr)
       @if_true.collect(arr)
-      @if_false.collect(arr)
+      @if_false.collect(arr) if @if_false
       super
     end
 

test/mom/test_if_simple_statement.rb

@@ -0,0 +1,29 @@
+require_relative "helper"
+
+module Mom
+  class TestSimpleIfMom < MiniTest::Test
+    include MomCompile
+
+    def setup
+      Risc.machine.boot
+      @stats = compile_first_method_flat( "if(@a == 5)  ; 5.mod4 ; end")
+      @first = @stats.next
+    end
+
+    def test_if_compiles
+      assert IfStatement != @stats.class , @stats
+    end
+    def test_check
+      assert_equal TruthCheck , @first.class
+    end
+    def test_condition_is_slot
+      assert_equal SlotDefinition , @first.condition.class , @first
+    end
+    def test_length
+      assert_equal 7 , @stats.length
+    end
+    def test_array
+      check_array [SlotMove,TruthCheck,Label,MessageSetup,SimpleCall,ArgumentTransfer,Label], @stats
+    end
+  end
+end