AutoFixture.Community.LoggerFactoryCustomizations

Extension to easily inject the abstract ILoggerFactory to your device under test.

What?

This extension to AutoFixture will create any logger from a test fixture without having to manually call fixture.Register<ILogger<MyClass>>(loggerFactory.CreateLogger<MyClass>()). Thus, reducing the code needed to push the logging output for example on the test output or using any compatible assertions for log messages, like the Serilog InMemoryLogSink.

Why?

In my ASP.NET Core / .NET Core projects I always use the logging abstractions provided by Microsoft. I like being able to check the quality of my log messages in my unit tests, too, without writing dedicated tests for my logging. As it was always quite a pain in the connector to my office chair registering each logger individually I thought it would be nice to have a decent extension method registering my provided logging factory in my test at my test fixture.

Example in XUnit2

I used the package Divergic.Logging.Xunit and Objectivity.AutoFixture.XUnit2.AutoMoq for this.

In the test case, it is possible to register the loggerfactory created in your test. You need to register your ILoggerFactory at the IFxiture using the provided extension method. It should show up when you are using the Autofixture namespace and have this package installed.

public class DemoTests
    {
        private readonly ILoggerFactory loggerFactory;

        public DemoTests(ITestOutputHelper toh)
        {
            loggerFactory = LogFactory.Create(toh);
        }
        [Theory, AutoMockData]
        public void HowToUseTest(IFixture fixture)
        {
            fixture.RegisterLoggerFactory(loggerFactory);
            var cut = fixture.Create<CutWithTestLogger>();

            cut.PrintLog();
        }
    }

    public class CutWithTestLogger
    {
        private readonly ILogger<CutWithTestLogger> logger;

        public CutWithTestLogger(ILogger<CutWithTestLogger> logger)
        {
            this.logger = logger;
        }

        public void PrintLog()
        {
            logger.LogInformation("Hello World");
        }
    }

This creates the following test output:

Information [0]: Hello World