fix: Modify logging behavior when explicitly adding NullLogger with custom config

[filzrev]

This PR intended to fix problem no console log is outputted when following conditions met.

• Using custom config that adding NullLogger explicitly
• Using custom config as Global Config (passing config as BenchmarkSwitcher::Run parameters)..

Currently BenchmarkDotNet use ConsoleLogger to print errors and list of benchmarks if logger is not enabled.
But when explicitly set NullLogger it's not works and no console logs are outputted.

Background

I'm trying to write custom progress logger that resolve #190 issue.
And it'll be implemented by using custom EventProcessor that is added from v0.13.9.

So It need to suppress default ConsoleLogger by adding NullLogger.
Because when no logger specified following error is recorded.

No loggers defined, you will not see any progress!

It works almost as intended.
But when passing custom config to BenchmarkSwitcher::Run argument. console log is not outputted.

[AndreyAkinshin]

@filzrev Sorry, but I do not understand the original problem. If we pass a custom config with NullLogger to BenchmarkRunner or BenchmarkSwitcher, it is expected that we will not see the output. What's wrong with this behavior?

[filzrev]

If we pass a custom config with NullLogger to BenchmarkRunner or BenchmarkSwitcher, it is expected that we will not see the output. What's wrong with this behavior?

The logger that is returned from GetNonNullCompositeLogger is used for following purpose.

• Print config parse errors
• Pring HostEnvironmentInfo
• Print --list outputs

BenchmarkDotNet/src/BenchmarkDotNet/Running/BenchmarkSwitcher.cs

Lines 93 to 123 in ca5dfdf

	var logger = notNullConfig.GetNonNullCompositeLogger();
	var (isParsingSuccess, parsedConfig, options) = ConfigParser.Parse(notNullArgs, logger, notNullConfig);
	if (!isParsingSuccess) // invalid console args, the ConfigParser printed the error
	return Array.Empty<Summary>();
	if (args == null && Environment.GetCommandLineArgs().Length > 1) // The first element is the executable file name
	logger.WriteLineHint("You haven't passed command line arguments to BenchmarkSwitcher.Run method. Running with default configuration.");
	if (options.PrintInformation)
	{
	logger.WriteLine(HostEnvironmentInfo.GetInformation());
	return Array.Empty<Summary>();
	}
	var effectiveConfig = ManualConfig.Union(notNullConfig, parsedConfig);
	var (allTypesValid, allAvailableTypesWithRunnableBenchmarks) = TypeFilter.GetTypesWithRunnableBenchmarks(types, assemblies, logger);
	if (!allTypesValid) // there were some invalid and TypeFilter printed errors
	return Array.Empty<Summary>();
	if (allAvailableTypesWithRunnableBenchmarks.IsEmpty())
	{
	userInteraction.PrintNoBenchmarksError(logger);
	return Array.Empty<Summary>();
	}
	if (options.ListBenchmarkCaseMode != ListBenchmarkCaseMode.Disabled)
	{
	PrintList(logger, effectiveConfig, allAvailableTypesWithRunnableBenchmarks, options);
	return Array.Empty<Summary>();
	}

And this logger is not used for running actual benchmarks.

I'm output console logs by using ConsoleLogger.Default (via custom EventProcessor).
So default console logs should be suppressed by setting NullLogger.

But when setting NullLogger to global config.
Above type of logs are also suppressed.

[filzrev]

Close this PR,
The reason is that the following workaround is available.

1. Add custom logger that delegate logging to ConsoleLogger.Default
2. Add custom EventProcessor. and when OnStartValidationStage is called. set custom logger to quiet mode