Render logs on exception

[colinangusmackay]

Set up a way to render logs when a test fails.

e.g.

public void Test()
{
  var logProvider = new TestCaptureLoggerProvider();
  using var rox = logProvider.RenderOnTestFailure(
    p => p.GetLogEntriesFor<ServiceBeingTested>(),
    Formatter.SimpleBySequence,
    Sink.Console);
  // do test stuff.

  rox.Success(); // If it gets here then logs are not rendered.
  // If the test method ends by throwing an exception the logs are automatically rendered.
  // i.e. rox is disposable, and if the success flag is not set, then anything that matches
  // the filter is rendered.
}

RenderOnTestFailure has three arguments

• A function that filters the captured logs. e.g. p => GetLogsWithExceptions()
• A formatter for rendering the log. e.g. l => $"[{le.LogLevel}] {le.FormattedMessage}"
• A sink for forwarding the rendered log. e.g. s => XunitOutputHelper.WriteLine(s)

This method is available on the log provider and the logger itself.