Support for testing multiple testcorrelator subloggers.

[leejeffr]

Is there a way to test sublogging using TestCorrelator?

For example, I want to verify that some logging events go to subLog1 and others go to sublog2.

What would happen below if both of my subloggers were of type TestCorrelator? I believe this test will fail because there will be two logevents. I'd like to test my filtering on subloggers and it seems reasonable to test that one sublogger recieved a particular event and other one didn't.

using (TestCorrelator.CreateContext())
{
    log.Debug("This is a test {A}", "ABC");
    log.Debug("Debug Sublogger");

    TestCorrelator.GetLogEventsFromCurrentContext().Should().ContainSingle();
}

[MitchBodmer]

There isn't a built in way for a sink to determine what called Emit on it. I think there are a few ways of handling this:

1. Break each assert into its own test and add the TestCorrelator to one sub-logger per test.
2. Create your sub-loggers by calling Log.ForContext with a property you can filter by.
3. In the example above you can just use two contexts.

[MitchBodmer]

There are ways we could support this behavior directly, but I'd have to give it a bit more thought.