Add unit test for hash code of class objects (#212)

***NO_CI***

Author: josesimoes

Tests/NFUnitTestClasses/NFUnitTestClasses.nfproj

@@ -36,6 +36,7 @@
     <Compile Include="UnitTestMethodsTests.cs" />
     <Compile Include="UnitTestOperatorTests.cs" />
     <Compile Include="UnitTestPropertiesTests.cs" />
+    <Compile Include="UnitTestHashCodeTests.cs" />
     <Compile Include="UnitTestStaticTests.cs" />
   </ItemGroup>
   <ItemGroup>

Tests/NFUnitTestClasses/UnitTestHashCodeTests.cs

@@ -0,0 +1,88 @@
+//
+// Copyright (c) .NET Foundation and Contributors
+// Portions Copyright (c) Microsoft Corporation.  All rights reserved.
+// See LICENSE file in the project root for full license information.
+//
+
+using nanoFramework.TestFramework;
+using System.Diagnostics;
+
+namespace NFUnitTestClasses
+{
+    [TestClass]
+    class UnitTestHashCodeTests
+    {
+        [TestMethod]
+        public void HashCode_Test_01()
+        {
+            // generate a hash code for a class with fields
+            SomeKey key = new(42);
+
+            int hashCode = key.GetHashCode();
+
+            OutputHelper.WriteLine($"Hash code for SomeKey(42) is {hashCode}");
+            OutputHelper.WriteLine($"Hash code for SomeKey(42) is {key.GetHashCode()}");
+
+            Assert.AreNotEqual(0, key.GetHashCode(), "Hash code for a class should not be 0");
+            Assert.AreEqual($"{key.GetHashCode()}".GetHashCode(), $"{hashCode}".GetHashCode());
+        }
+
+        [TestMethod]
+        public void HashCode_Test_02()
+        {
+            // generate a hash code for a class without fields
+            SomeOtherKey key = new();
+
+            int hashCode = key.GetHashCode();
+
+            OutputHelper.WriteLine($"Hash code for SomeOtherKey is {hashCode}");
+            OutputHelper.WriteLine($"Hash code for SomeOtherKey is {key.GetHashCode()}");
+
+            Assert.AreNotEqual(0, key.GetHashCode(), "Hash code for a class should not be 0");
+            Assert.AreEqual($"{key.GetHashCode()}".GetHashCode(), $"{hashCode}".GetHashCode());
+        }
+
+        [TestMethod]
+        public void HashCode_Test_03()
+        {
+            // generate a hash code for a class with fields with different types
+            SomeOtherFunnyKey key = new();
+
+            int hashCode = key.GetHashCode();
+
+            OutputHelper.WriteLine($"Hash code for SomeOtherFunnyKey is {hashCode}");
+            OutputHelper.WriteLine($"Hash code for SomeOtherFunnyKey is {key.GetHashCode()}");
+
+            Assert.AreNotEqual(0, key.GetHashCode(), "Hash code for a class should not be 0");
+            Assert.AreEqual($"{key.GetHashCode()}".GetHashCode(), $"{hashCode}".GetHashCode());
+        }
+
+        public class SomeKey
+        {
+            public SomeKey(int value)
+            {
+                Value = value;
+            }
+            public int Value { get; }
+        }
+
+        public class SomeOtherKey
+        {
+            public SomeOtherKey()
+            {
+            }
+        }
+
+        public class SomeOtherFunnyKey
+        {
+            public string Name { get; set; }
+
+            public int GetValue { get; set; }
+
+            public SomeOtherFunnyKey()
+            {
+            }
+        }
+
+    }
+}