diff --git a/test/mom/instruction/helper.rb b/test/mom/instruction/helper.rb
new file mode 100644
index 00000000..e527e429
--- /dev/null
+++ b/test/mom/instruction/helper.rb
@@ -0,0 +1,13 @@
+require_relative '../helper'
+
+module Mom
+  class CompilerMock
+    def use_reg( type )
+      Risc.tmp_reg(type , nil)
+    end
+    def add_constant(c)
+    end
+  end
+  class InstructionMock < Instruction
+  end
+end
diff --git a/test/mom/instruction/test_slot_definition.rb b/test/mom/instruction/test_slot_definition.rb
new file mode 100644
index 00000000..d822ce87
--- /dev/null
+++ b/test/mom/instruction/test_slot_definition.rb
@@ -0,0 +1,54 @@
+require_relative "helper"
+
+module Mom
+  class TestSlotDefinitionBasics < MiniTest::Test
+
+    def slot(slot = :caller)
+      SlotDefinition.new(:message , slot)
+    end
+    def test_create_ok1
+      assert_equal :message , slot.known_object
+    end
+    def test_create_ok2
+      assert_equal Array , slot.slots.class
+      assert_equal :caller , slot.slots.first
+    end
+    def test_create_fail_none
+      assert_raises {slot(nil)}
+    end
+  end
+  class TestSlotDefinitionConstant < MiniTest::Test
+    def setup
+      Risc.machine.boot
+      @compiler = CompilerMock.new
+      @definition = SlotDefinition.new(StringConstant.new("hi") , [])
+      @instruction = @definition.to_register(@compiler , InstructionMock.new)
+    end
+    def test_def_class
+      assert_equal Risc::LoadConstant , @instruction.class
+    end
+    def test_def_register
+      assert_equal :r1 , @instruction.register.symbol
+    end
+    def test_def_const
+      assert_equal "hi" , @instruction.constant.to_string
+    end
+  end
+  class TestSlotDefinitionKnown1 < MiniTest::Test
+    def setup
+      Risc.machine.boot
+      @compiler = CompilerMock.new
+      @definition = SlotDefinition.new(:message , :caller)
+      @instruction = @definition.to_register(@compiler , InstructionMock.new)
+    end
+    def test_def_class
+      assert_equal Risc::SlotToReg , @instruction.class
+    end
+    def test_def_array
+      assert_equal :r0 , @instruction.array.symbol
+    end
+    def test_def_register
+      assert_equal :r1 , @instruction.register.symbol
+    end
+  end
+end
diff --git a/test/mom/instruction/test_slot_load.rb b/test/mom/instruction/test_slot_load.rb
new file mode 100644
index 00000000..da034898
--- /dev/null
+++ b/test/mom/instruction/test_slot_load.rb
@@ -0,0 +1,13 @@
+require_relative "helper"
+
+module Mom
+  class TestSlotLoad < MiniTest::Test
+
+    def setup
+    end
+
+    def test_while_instructions
+      assert_nil nil
+    end
+  end
+end