Verify.MicrosoftLogging

Extends Verify to allow verification of MicrosoftLogging bits.

See Milestones for release notes.

NuGet package

https://nuget.org/packages/Verify.MicrosoftLogging/

Usage

[ModuleInitializer]
public static void Initialize() =>
    VerifyMicrosoftLogging.Initialize();

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Logging Recording allows, when a method is being tested, for any logging made as part of that method call to be recorded and verified.

Call LoggerRecording.Start(); to get an instance of the LoggerProvider. LoggerProvider implements both ILogger and ILoggerProvider.

The pass in the LoggerProvider instance to a class/method that write log entries:

[Fact]
public Task Logging()
{
    var provider = LoggerRecording.Start();
    var target = new ClassThatUsesLogging(provider);

    var result = target.Method();

    return Verify(result);
}

class ClassThatUsesLogging(ILogger logger)
{
    public string Method()
    {
        logger.LogWarning("The log entry");
        using (logger.BeginScope("The scope"))
        {
            logger.LogWarning("Entry in scope");
        }

        return "result";
    }
}

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Results in:

{
  target: result,
  logs: [
    {
      Warning: The log entry
    },
    {
      Message: StartScope,
      State: The scope
    },
    {
      Warning: Entry in scope
    },
    {
      Message: EndScope
    }
  ]
}

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Typed

A common pattern is to use a type logger (Logger<T>). LoggerProvider provides a builder method CreateLogger<T> to construct a Logger<T>:

[Fact]
public Task LoggingTyped()
{
    var provider = LoggerRecording.Start();
    var logger = provider.CreateLogger<ClassThatUsesTypedLogging>();
    ClassThatUsesTypedLogging target = new(logger);

    var result = target.Method();

    return Verify(result);
}

class ClassThatUsesTypedLogging
{
    ILogger<ClassThatUsesTypedLogging> logger;

    public ClassThatUsesTypedLogging(ILogger<ClassThatUsesTypedLogging> logger) =>
        this.logger = logger;

    public string Method()
    {
        logger.LogWarning("The log entry");
        return "result";
    }
}

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Results in:

{
  target: result,
  logs: [
    {
      Warning: The log entry,
      Category: ClassThatUsesTypedLogging
    }
  ]
}

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