Fix Guid constructor (#259)

***NO_CI***

Author: josesimoes

Tests/NFUnitTestSystemLib/UnitTestInitLocalTests.cs

@@ -215,14 +215,24 @@ public void SystemType1_ArrayListToArrayForStruct_Test()
             // make sure boxing of struct value type (Guid) is handled properly
             // this test was a result of a bug found by a customer.
             Guid ret = new Guid();
+
             ArrayList guidList = new ArrayList();
             guidList.Add(Guid.NewGuid());
             guidList.Add(Guid.NewGuid());
+
             Guid[] guidArray = (Guid[])guidList.ToArray(typeof(Guid));
 
+            // Verify the array has the correct length
+            Assert.AreEqual(2, guidArray.Length);
+
+            // Verify each element is not empty and matches the source list
+            int i = 0;
             foreach (Guid g in guidArray)
             {
+                Assert.IsFalse(Guid.Empty.Equals(g), "Guid should not be empty");
+                Assert.AreEqual(guidList[i], g, "Guid should match the source ArrayList element");
                 ret = g;
+                i++;
             }
         }
 

Tests/NFUnitTestTypes/UnitTestGuid.cs

@@ -99,15 +99,15 @@ public void Guid_TryParseGuidWithDashes_Valid()
         {
             var g1 = Guid.NewGuid();
             var str = g1.ToString();
-            bool parsed = Guid.TryParseGuidWithDashes(str, out var g2);
+            bool parsed = Guid.TryParse(str, out var g2);
             Assert.IsTrue(parsed);
             Assert.AreEqual(g1, g2);
         }
 
         [TestMethod]
         public void Guid_TryParseGuidWithDashes_Invalid()
         {
-            bool parsed = Guid.TryParseGuidWithDashes("invalid-guid", out var g2);
+            bool parsed = Guid.TryParse("invalid-guid", out var g2);
             Assert.IsFalse(parsed);
             Assert.AreEqual(Guid.Empty, g2);
         }

nanoFramework.CoreLibrary/System/Guid.cs

@@ -11,19 +11,13 @@ namespace System
     [Serializable]
     public struct Guid
     {
-        private int[] _data;
+        private int[] _data = new int[4];
 
         /// <summary>
         /// A read-only instance of the Guid class which consists of all zeros.
         /// </summary>
         public static readonly Guid Empty = new Guid(new byte[16]);
 
-        public Guid()
-        {
-            // All zeros
-            _data = new int[4]; 
-        }
-
         /// <summary>
         /// Initializes a new instance of the <see cref="Guid"/> structure by using the specified integers and bytes.
         /// </summary>