Why am I getting this error from NLog during integration testing: LayoutRenderer cannot be found - asp.net-core

Question

I added some aspnet layout renderers to my NLog configuration, and everything works fine for my website, but when I try to run my integration tests, they fail with this error message:
NLog.NLogConfigurationException : Error when setting property 'Layout' on NLog.Targets.DatabaseParameterInfo
----> System.ArgumentException : LayoutRenderer cannot be found: 'aspnet-request-cookie'. Is NLog.Web not included?
My initial instinct was to follow their suggestion and add the NLog.Web.AspNetCore package to my integration Test project. That did not do anything.
Here's what my integration test setup looks like:
[OneTimeSetUp]
public static void BaseOneTimeSetUp()
{
var environment = Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT") ?? "Development";
Assume.That(environment, Is.AnyOf("Development", "CI"), "Integration tests can only run in one of those environments");
var serviceCollection = new ServiceCollection();
serviceCollection.AddSingleton<IHostingEnvironment>(p =>
{
var mock = new Mock<IHostingEnvironment>();
mock.SetupGet(m => m.ContentRootPath).Returns(TestContext.CurrentContext.TestDirectory);
mock.SetupGet(m => m.EnvironmentName).Returns(environment);
return mock.Object;
});
Startup.AddConfiguration(serviceCollection); //throws NLogConfigurationException
}
And here's my implementation for the Startup AddConfiguration method:
public static void AddConfiguration(IServiceCollection services)
{
services.AddSingleton<IConfiguration>(s =>
{
var env = s.GetService<IHostingEnvironment>();
var builder = new ConfigurationBuilder()
.SetBasePath(env.ContentRootPath)
.AddJsonFile("appsettings.json", false, true)
.AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
.AddEnvironmentVariables();
var config = builder.Build();
// This next line throws the NLogConfigurationException
LogManager.Configuration = new NLogLoggingConfiguration(config.GetSection("NLog"));
return config;
});
}

Answer 1

The integration test is not calling the UseNLog method for the asp.net WebHost, as shown in their example code:
WebHost.CreateDefaultBuilder(args)
.UseStartup<Startup>()
.ConfigureLogging(logging =>
{
logging.ClearProviders();
logging.SetMinimumLevel(Microsoft.Extensions.Logging.LogLevel.Trace);
})
.UseNLog(); // NLog: setup NLog for Dependency injection
If you don't want to set up a WebHost for your tests, you can make do with a Mock<IWebHostBuilder>.
All you need to do is add this to your test setup before configuring NLog:
var mockHostBuilder = new Mock<IWebHostBuilder>();
mockHostBuilder.Object.UseNLog();