Make setter make more sense

SabreTools.Test/DatFiles/SetterTests.cs

@@ -0,0 +1,52 @@
+using System.Collections.Generic;
+
+using SabreTools.Core;
+using SabreTools.DatFiles;
+using SabreTools.DatItems;
+using Xunit;
+
+namespace SabreTools.Test.DatFiles
+{
+    public class SetterTests
+    {
+        [Fact]
+        public void SetFieldsDatItemTest()
+        {
+            var datItem = CreateDatItem();
+            Setter setter = new Setter
+            {
+                DatItemMappings = new Dictionary<DatItemField, string> { [DatItemField.Name] = "bar" }
+            };
+            setter.SetFields(datItem);
+            Assert.Equal("bar", datItem.GetName());
+        }
+
+        [Fact]
+        public void SetFieldsMachineTest()
+        {
+            var datItem = CreateDatItem();
+            Setter setter = new Setter
+            {
+                MachineMappings = new Dictionary<MachineField, string> { [MachineField.Name] = "foo" }
+            };
+            setter.SetFields(datItem.Machine);
+            Assert.Equal("foo", datItem.Machine.Name);
+        }
+
+        /// <summary>
+        /// Generate a consistent DatItem for testing
+        /// </summary>
+        private DatItem CreateDatItem()
+        {
+            return new Rom
+            {
+                Name = "foo",
+                Machine = new Machine
+                {
+                    Name = "bar",
+                    Description = "bar",
+                }
+            };
+        }
+    }
+}