Serilog.Sinks.TestCorrelator

A Serilog sink that correlates log events with the code that produced them, enabling unit testing of log output.

Usage

Just create a logger that writes or audits to the TestCorrelator.

Log.Logger = new LoggerConfiguration().WriteTo.TestCorrelator().CreateLogger();

Then wrap the code that you would like to monitor with a context and get the log events emitted within that context using the TestCorrelator.

using (TestCorrelator.CreateContext())
{
    Log.Information("My log message!");

    TestCorrelator.GetLogEventsFromCurrentContext()
        .Should().ContainSingle()
        .Which.MessageTemplate.Text
        .Should().Be("My log message!");
}

You can also get a stream of log events as an observable, which can be useful for testing long running or asynchronous tasks.

using (TestCorrelator.CreateContext())
{
    TestCorrelator.GetLogEventStreamFromCurrentContext()
        .Subscribe(logEvent => logEvent.MessageTemplate.Text.Should().Be("My log message!"));

    Log.Information("My log message!");
}

New in v4: If you have more than one logger and want to filter to only log events emitted to a specific sink you can pass in an ID that you then use to filter the log events.

TestCorrelatorSinkId firstTestCorrelatorSinkId = new();
ILogger firstLogger = new LoggerConfiguration().WriteTo.TestCorrelator(firstTestCorrelatorSinkId).CreateLogger();

TestCorrelatorSinkId secondTestCorrelatorSinkId = new();
ILogger secondLogger = new LoggerConfiguration().WriteTo.TestCorrelator(secondTestCorrelatorSinkId).CreateLogger();

using (TestCorrelator.CreateContext())
{
    firstLogger.Information("My first log message!");
    secondLogger.Information("My second log message!");

    TestCorrelator.GetLogEventsForSinksFromCurrentContext(firstTestCorrelatorSinkId)
        .Should().ContainSingle()
        .Which.MessageTemplate.Text
        .Should().Be("My first log message!");

    TestCorrelator.GetLogEventsForSinksFromCurrentContext(secondTestCorrelatorSinkId)
        .Should().ContainSingle()
        .Which.MessageTemplate.Text
        .Should().Be("My second log message!");
}

For more examples check out the unit tests!

v4 Breaking Changes

Version 4 comes with a few breaking changes.

• All package dependencies have been updated.
• Dropped support for .Net Framework 4.6.1 and below. This brings the package in line with Serilog's supported frameworks.
• A new TestCorrelatorContextId class is not being used instead of Guids. The corresponding ...ContextGuid() methods have been renamed to ...ContextId().
• LogEvents emitted outside of a context are no longer captured.
• LoggerConfiguration extension methods with implicitly ignored minimum LogEventLevel parameters were removed.