Added tests

Tests/Musify.Application.Tests/Extensions/ResultExtensionsTests.cs

@@ -0,0 +1,74 @@
+using Ardalis.Result;
+using FluentAssertions;
+using Musify.Application.Extensions;
+using Xunit;
+
+namespace Musify.Application.Tests.Extensions;
+
+public sealed class ResultExtensionsTests
+{
+    [Fact]
+    public void NotFound_maps_to_NotFound_and_preserves_errors()
+    {
+        var source = Result<int>.NotFound("missing");
+
+        var mapped = source.As<int, string>();
+
+        mapped.Status.Should().Be(ResultStatus.NotFound);
+        mapped.Errors.Should().Contain("missing");
+    }
+
+    [Fact]
+    public void Conflict_maps_to_Conflict()
+    {
+        Result<int>.Conflict("dup").As<int, string>().Status.Should().Be(ResultStatus.Conflict);
+    }
+
+    [Fact]
+    public void Unauthorized_maps_to_Unauthorized()
+    {
+        Result<int>.Unauthorized().As<int, string>().Status.Should().Be(ResultStatus.Unauthorized);
+    }
+
+    [Fact]
+    public void Forbidden_maps_to_Forbidden()
+    {
+        Result<int>.Forbidden().As<int, string>().Status.Should().Be(ResultStatus.Forbidden);
+    }
+
+    [Fact]
+    public void Invalid_maps_to_Invalid_and_preserves_validation_errors()
+    {
+        var source = Result<int>.Invalid(new ValidationError("field", "bad"));
+
+        var mapped = source.As<int, string>();
+
+        mapped.Status.Should().Be(ResultStatus.Invalid);
+        mapped.ValidationErrors.Should().ContainSingle(e => e.ErrorMessage == "bad");
+    }
+
+    [Fact]
+    public void Error_maps_to_Error()
+    {
+        Result<int>.Error("boom").As<int, string>().Status.Should().Be(ResultStatus.Error);
+    }
+
+    [Theory]
+    [InlineData(ResultStatus.Ok)]
+    [InlineData(ResultStatus.Created)]
+    [InlineData(ResultStatus.NoContent)]
+    public void Successful_results_throw_when_converted(ResultStatus status)
+    {
+        Result<int> source = status switch
+        {
+            ResultStatus.Ok => Result<int>.Success(1),
+            ResultStatus.Created => Result<int>.Created(1),
+            ResultStatus.NoContent => Result<int>.NoContent(),
+            _ => throw new InvalidOperationException()
+        };
+
+        var act = () => source.As<int, string>();
+
+        act.Should().Throw<InvalidOperationException>();
+    }
+}