feat(Extension): Result supports Nullable Value and Error

sample/ConsoleApp/Pipelines/CreateUserPipeline.cs

@@ -41,7 +41,9 @@ private static Maybe<User> LookupUser(Username username)
 
     private static Result<User> CreateUser(User user)
     {
+#pragma warning disable CS0162 // Unreachable code detected
         if (false) return Result.Failure<User>("Error creating user");
+#pragma warning restore CS0162 // Unreachable code detected
         return new(user);
     }
     private static void NotifyCreation(User user)

src/Monads/Result/Result.cs

@@ -150,8 +150,15 @@ public static async Task<Result<TValue>> Execute<TValue>(Func<Task<TValue>> func
 /// <typeparam name="TValue"></typeparam>
 public readonly struct Result<TValue> : IResult<TValue>, IEquatable<Result<TValue>>, IEnumerable<TValue>
 {
-    internal readonly TValue? Value;
-    internal readonly Error? Error;
+    /// <summary>
+    /// The value of the <see cref="Result{TValue}"/> if the <see cref="IsSuccess"/> is <c>true</c>.
+    /// </summary>
+    public TValue? Value { get; }
+
+    /// <summary>
+    /// The error of the <see cref="Result{TValue}"/> if the <see cref="IsFailure"/> is <c>true</c>.
+    /// </summary>
+    public Error? Error { get; }
 
     /// <summary>
     /// Initializes a successful instance of the <see cref="Result{TValue}"/> with the given <paramref name="value"/>.

test/Monads.UnitTests/ResultTests/ResultValueTests.cs

@@ -0,0 +1,31 @@
+namespace Bogoware.Monads.UnitTests.ResultTests;
+
+public class ResultValueTests
+{
+    [Fact]
+    public void Success_returns_itsValue_andNullError()
+    {
+        var sut = Result.Success(new Value(666));
+
+        sut.Value.Should().NotBeNull();
+        sut.Error.Should().BeNull();
+    }
+
+    [Fact]
+    public void Failure_returns_nullValue_andItsError()
+    {
+        var sut = Result.Failure<Value>("Error");
+
+        sut.Value.Should().BeNull();
+        sut.Error.Should().NotBeNull();
+    }
+
+    [Fact]
+    public void Failure_returns_defaultValue_andItsError()
+    {
+        var sut = Result.Failure<Guid>("Error");
+
+        sut.Value.Should().Be(default(Guid));
+        sut.Error.Should().NotBeNull();
+    }
+}