Complete overhaul on Skippers

This change involves safety updates for serialization, better definitions of various classes, renames of some classes for accuracy, missing enum decoration, and various fixes.

SabreTools.Skippers/Tests/FileTest.cs

@@ -0,0 +1,87 @@
+using System;
+using System.IO;
+using System.Xml;
+using System.Xml.Serialization;
+
+namespace SabreTools.Skippers.Tests
+{
+    /// <summary>
+    /// Test that tests file size
+    /// </summary>
+    [XmlType("file")]
+    public class FileTest : Test
+    {
+        #region Fields
+
+        /// <summary>
+        /// Determines whether a pass or failure is expected
+        /// </summary>
+        [XmlAttribute("result")]
+        public bool Result { get; set; } = true;
+
+        /// <summary>
+        /// Expected size of the input byte array, used with the Operator
+        /// </summary>
+        /// <remarks>Either numeric or the literal "po2"</remarks>
+        [XmlAttribute("size")]
+        public string Size
+        {
+            get => _size == null ? "po2" : _size.Value.ToString();
+            set
+            {
+                if (value == null || value.ToLowerInvariant() == "po2")
+                    _size = null;
+                else
+                    _size = Convert.ToInt64(value, fromBase: 16);
+            }
+        }
+
+        /// <summary>
+        /// Expected range value for the input byte array size, used with Size
+        /// </summary>
+        [XmlAttribute("operator")]
+        public HeaderSkipTestFileOperator Operator { get; set; }
+
+        #endregion
+
+        #region Private instance variables
+
+        /// <summary>
+        /// File offset to run the test
+        /// </summary>
+        /// <remarks>null is PO2 ("power of 2" filesize)</remarks>
+        private long? _size;
+
+        #endregion
+
+        /// <inheritdoc/>
+        public override bool Passes(Stream input)
+        {
+            // First get the file size from stream
+            long size = input.Length;
+
+            // If we have a null size, check that the size is a power of 2
+            bool result = true;
+            if (_size == null)
+            {
+                // http://stackoverflow.com/questions/600293/how-to-check-if-a-number-is-a-power-of-2
+                result = (((ulong)size & ((ulong)size - 1)) == 0);
+            }
+            else if (Operator == HeaderSkipTestFileOperator.Less)
+            {
+                result = (size < _size);
+            }
+            else if (Operator == HeaderSkipTestFileOperator.Greater)
+            {
+                result = (size > _size);
+            }
+            else if (Operator == HeaderSkipTestFileOperator.Equal)
+            {
+                result = (size == _size);
+            }
+
+            // Return if the expected and actual results match
+            return result == Result;
+        }
+    }
+}