five minutes spent mashing together Rx and LibGit2Sharp

ObservableRepository.cs

using System;
using System.Reactive.Linq;
using LibGit2Sharp;

namespace ReactiveGit
{
    public class ObservableRepository : IDisposable
    {
        readonly Repository _repository;

        public ObservableRepository(string directory)
        {
            _repository = new Repository(directory);
        }

        public IObservable<MergeResult> Pull(IObserver<Tuple<string, int>> observer)
        {
            var signature = _repository.Config.BuildSignature(DateTimeOffset.Now);
            var options = new PullOptions
            {
                MergeOptions = new MergeOptions
                {
                    OnCheckoutProgress = (s, completedSteps, totalSteps) =>
                    {
                        // surface the progress from libgit2
                        var progress = (100 * completedSteps) / totalSteps;
                        observer.OnNext(Tuple.Create(s, progress));
                    }
                }
            };

            // this is a blocking call, hence all the ceremony before
            return Observable.Start(() => _repository.Network.Pull(signature, options))
                .Finally(() =>
                {
                    // ensure the observable signals even when the branch is up to date
                    observer.OnNext(Tuple.Create("pull completed", 100));
                    observer.OnCompleted();
                });
        }

        public void Dispose()
        {
            _repository.Dispose();
        }
    }
}

ObservableRepositoryTests.cs

using System;
using System.Reactive;
using System.Reactive.Concurrency;
using System.Reactive.Linq;
using System.Threading.Tasks;
using LibGit2Sharp;
using Xunit;

namespace ReactiveGit.Tests
{
    public class ObservableRepositoryTests
    {
        [Fact]
        public async Task CanPullSomeRepository()
        {
            var repository = new ObservableRepository(
                @"C:\Users\brendanforster\Documents\GìtHūb\atom-dark-syntax");

            var progress = Observer.Create<Tuple<string, int>>(
                next => { Console.WriteLine("progress: " + next.Item2); },
                () => { Console.WriteLine("it is done"); })
                .NotifyOn(DefaultScheduler.Instance);

            var result = await repository.Pull(progress);

            Assert.NotEqual(MergeStatus.Conflicts, result.Status);
        }
    }
}

The real power in this approach, is when the value you pass into progress is a Subject, which means you can start using Rx operators on the progress output.

I think you need some spaces and single quotes along with the accented characters in your GitHub path ;)