Exceptions thrown in CreateFromTask(...).Subscribe behave differently than those thrown in CreateFromObservable(...).Subscribe

[philipkaare]

I have two unit tests below, only difference is in how the observable is created. In CreateFromTask the observable is not created using the scheduler, whereas when I do myself the exception bubbles up.

I am not sure if this is intended or not -> in general I find the behavior of exceptions in the different command types to be confusing. Is there some guiding principle I should be following when it comes to exceptions?

Thanks!

Code:

  [Fact]
  public void TestExceptionBugFails()
  {
      new TestScheduler().With(s =>
      {
          Assert.Throws<Exception>(() =>
          {
              var command = ReactiveCommand.CreateFromTask(async () =>
              {
                  await s.Sleep(TimeSpan.FromSeconds(1));
              }, null, s);
              command.Execute().Subscribe(_ =>
              {
                  throw new Exception();
              });
          });
          
          s.Start();
          s.AdvanceBy(TimeSpan.FromSeconds(1).Ticks);

      });
  }

  [Fact]
  public void TestExceptionBugPasses()
  {
      new TestScheduler().With(s =>
      {
          Assert.Throws<Exception>(() =>
          {
              var task = async () => { await s.Sleep(TimeSpan.FromSeconds(1)); };

              var command = ReactiveCommand.CreateFromObservable(() => task().ToObservable(s));
              command.Execute().Subscribe(_ => throw new Exception());

              s.Start();
              s.AdvanceBy(TimeSpan.FromSeconds(1).Ticks);
          });
      });
  }