Just.Railway/Raliway.Tests/Results/GeneralUsage.cs

namespace Raliway.Tests.Results;

public class GeneralUsage
{
    [Fact]
    public void ChainedResultExtensions_WhenThereIsNoError()
    {
        // Given

        // When
        var result = Result.Success()
            .Append(() => Result.Success(1))
            .Append("test")
            .Map((i, s) => $"{s}_{i}")
            .Append("some")
            .Bind((s1, s2) => Result.Success(string.Join(';', s1, s2)))
            .Match(
                onSuccess: s => s.ToUpper(),
                onFailure: _ =>
                {
                    true.ShouldBeFalse("should not reach this path");
                    return "";
                }
            );

        result.ShouldBe("TEST_1;SOME");
    }

    [Fact]
    public void ChainedResultExtensions_WhenThereIsAnError()
    {
        // Given
        var error = Error.New("test");

        // When

        var result = Result.Success()
            .Append(() => Result.Failure<int>(error))
            .Append("test")
            .Map((i, s) =>
            {
                true.ShouldBeFalse("should not reach this path");
                return "";
            })
            .Append("some")
            .Bind((s1, s2) =>
            {
                true.ShouldBeFalse("should not reach this path");
                return Result.Success("");
            })
            .Match(
                onSuccess: _ =>
                {
                    true.ShouldBeFalse("should not reach this path");
                    return "";
                },
                onFailure: err =>
                {
                    err.ShouldBe(error);
                    return "satisfied";
                }
            );

        // Then
        result.ShouldBe("satisfied");
    }

    [Fact]
    public async Task ChainedResultAsyncExtensions_WhenThereIsNoError()
    {
        // Given

        // When
        var result = await Result.Success()
            .Append(() => Task.FromResult(Result.Success(1)))
            .Append("test")
            .Map((i, s) => $"{s}_{i}")
            .Append("some")
            .Bind(async (s1, s2) => await ValueTask.FromResult(Result.Success(string.Join(';', s1, s2))))
            .Match(
                onSuccess: s => s.ToUpper(),
                onFailure: _ =>
                {
                    true.ShouldBeFalse("should not reach this path");
                    return "";
                }
            );
        
        result.ShouldBe("TEST_1;SOME");
    }

    [Fact]
    public async Task ChainedResultAsyncExtensions_WhenThereIsAnError()
    {
        // Given
        var error = Error.New("test");

        // When

        var result = await Result.Success()
            .Append(() => Task.FromResult(Result.Failure<int>(error)))
            .Append("test")
            .Map((i, s) =>
            {
                true.ShouldBeFalse("should not reach this path");
                return "";
            })
            .Append("some")
            .Bind(async (s1, s2) => 
            {
                true.ShouldBeFalse("should not reach this path");
                await Task.CompletedTask;
                return Result.Success("");
            })
            .Match(
                onSuccess: _ =>
                {
                    true.ShouldBeFalse("should not reach this path");
                    return "";
                },
                onFailure: err =>
                {
                    err.ShouldBe(error);
                    return "satisfied";
                }
            );

        // Then
        result.ShouldBe("satisfied");
    }

    [Fact]
    public void RecoverResultFromFailureState()
    {
        // Given
        Result<string> failed = new NotImplementedException();
        // When
        var result = failed.TryRecover(err => 
        {
            err.ToException().ShouldBeOfType<NotImplementedException>();

            if (err.Type == "System.NotImplementedException")
                return "recovered";

            true.ShouldBeFalse("should not reach this path");
            return "";
        });
        // Then
        result.IsSuccess.ShouldBeTrue();
        result.Value.ShouldBe("recovered");
    }

    [Fact]
    public void WhenCanNotRecoverResultFromFailureState()
    {
        // Given
        var error = Error.New("test");
        Result<string> failed = new NotImplementedException();
        // When
        var result = failed.TryRecover(err =>
        {
            if (err.Type == "System.NotImplementedException")
                return error;
            
            true.ShouldBeFalse("should not reach this path");
            return "";
        });
        // Then
        result.IsFailure.ShouldBeTrue();
        result.Error.ShouldBe(error);
    }

    [Fact]
    public void WhenExtendingSuccessWithSuccess_ShouldReturnSuccess()
    {
        var success = Result.Success(1)
            .Append("2");

        var result = success
            .Extend((i, s) => Result.Success($"{i} + {s}"));

        result.IsSuccess.ShouldBeTrue();
        result.Value.ShouldBe((1, "2", "1 + 2"));
    }

    [Fact]
    public void WhenExtendingFailureWithSuccess_ShouldNotEvaluateExtension()
    {
        var failure = Result.Success(1)
            .Append(Result.Failure<string>("failure"));

        var result = failure
            .Extend((i, s) =>
            {
                true.ShouldBeFalse("should not reach this path");
                return Result.Success("");
            });

        result.IsFailure.ShouldBeTrue();
        result.Error.ShouldBe(Error.New("failure"));
    }

    [Fact]
    public void WhenExtendingSuccessWithFailure_ShouldReturnFailure()
    {
        var success = Result.Success(1)
            .Append("2");

        var result = success
            .Extend((i, s) => Result.Failure<string>("failure"));

        result.IsFailure.ShouldBeTrue();
        result.Error.ShouldBe(Error.New("failure"));
    }
}