Adding test for value function

pkg/models/mto_service_items_test.go

@@ -110,3 +110,31 @@ func (suite *ModelSuite) TestFetchRelatedDestinationSITServiceItems() {
 		suite.Len(relatedServiceItems, 0, "There should be zero related destination service items")
 	})
 }
+
+func (suite *ModelSuite) TestValue() {
+	suite.Run("value returns an array", func() {
+		move := factory.BuildMove(suite.DB(), nil, nil)
+		shipment := factory.BuildMTOShipment(suite.DB(), []factory.Customization{
+			{
+				Model:    move,
+				LinkOnly: true,
+			},
+		}, nil)
+		msServiceItem := factory.BuildMTOServiceItem(suite.DB(), []factory.Customization{
+			{
+				Model:    shipment,
+				LinkOnly: true,
+			},
+			{
+				Model: models.ReService{
+					Code: models.ReServiceCodeMS,
+				},
+			},
+		}, nil)
+
+		byte, err := msServiceItem.Value()
+
+		suite.NotNil(byte)
+		suite.Nil(err)
+	})
+}