Not sure why the AppVeyor CI build has started producing flaky results around LogContext - will keep an eye on it, but pretty sure it's not related to this PR 👍

Maybe some unit tests to add :

• Asking for Logger.None twice returns the same instance (i.e. it's not a neweach time)
• the result of new LoggerConfiguration().CreateLogger() is Logger.None

@tsimbalar - I've addressed your first suggestion.
The second though is a little more work and may warrant some discussion with @nblumhardt first.

This test

        [Fact]
        public void EmptyLoggerConfigurationCreatesNoneLogger()
        {
            var emptyConfigLogger = new LoggerConfiguration().CreateLogger();
            var noneLongger = Logger.None;

            Assert.Equal(emptyConfigLogger, noneLongger);
        }

fails.

We could modify CreateLogger() to see that there's zero configuration and thus deliberately return Logger.None. It doesn't do that now. SilentLogger itself is barely used in the Serilog codebase (apart from the tests). Certainly there's no way you could get one from CreateLogger() as the code stands now (which surprised me given the chat in issue #1105)

@nblumhardt - should we do this at all? If so, want it in a separate PR? I've only had a cursory look at LoggerConfiguration.cs and I can think of a couple of approaches - one to check for any methods/setters being called and set a flag so we know not to short-circuit return Logger.None. The other, which is less invasive but may not be quite correct, would be to have CreateLogger() see if everything is still at the defaults (empty sinks list, etc), and if so, just return Logger.None.

Con against doing it... If you really want a silent logger, use the .None property rather than the hacky 'empty configuraton' approach.

@IanYates oh my bad, I thought that was the actual behavior ... I may be mixed up ... The test that should pass as of now, though, is that Log.Logger should be a SilentLogger by default, if not assigned otherwise ... should it actually be Logger.None ?

Great suggestions @tsimbalar 👍

In v1.x, CreateLogger() did return the SilentLogger. But, in v2, we switched the return type of CreateLogger from ILogger to Logger so that the need to dispose the result was communicated by the API.

I think this is ready to go; no idea why the CI build is suddenly unhappy, but guess that's something to figure out another day :-)