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<img src="/src/icon.png" height="30px"> Verify.MicrosoftLogging

Extends Verify to allow verification of MicrosoftLogging bits.

See Milestones for release notes.

NuGet package

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

Usage

<a id='snippet-Enable'></a>

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

^{<a href='/src/Tests/ModuleInitializer.cs#L3-L9' title='Snippet source file'>snippet source</a> | <a href='#snippet-Enable' title='Start of snippet'>anchor</a>}

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:

<a id='snippet-LoggerRecording'></a>

[Fact]
public Task Logging()
{
    Recording.Start();
    var logger = new RecordingLogger();
    var target = new ClassThatUsesLogging(logger);

    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";
    }
}

^{<a href='/src/Tests/Tests.cs#L49-L77' title='Snippet source file'>snippet source</a> | <a href='#snippet-LoggerRecording' title='Start of snippet'>anchor</a>}

Results in:

<a id='snippet-Tests.Logging.verified.txt'></a>

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

^{<a href='/src/Tests/Tests.Logging.verified.txt#L1-L18' title='Snippet source file'>snippet source</a> | <a href='#snippet-Tests.Logging.verified.txt' title='Start of snippet'>anchor</a>}

Typed

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

<a id='snippet-LoggerRecordingTyped'></a>

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

    var result = target.Method();

    return Verify(result);
}

class ClassThatUsesTypedLogging(ILogger<ClassThatUsesTypedLogging> logger)
{
    public string Method()
    {
        logger.LogWarning("The log entry");
        return "result";
    }
}

^{<a href='/src/Tests/Tests.cs#L5-L28' title='Snippet source file'>snippet source</a> | <a href='#snippet-LoggerRecordingTyped' title='Start of snippet'>anchor</a>}

Results in:

<a id='snippet-Tests.LoggingTyped.verified.txt'></a>

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

^{<a href='/src/Tests/Tests.LoggingTyped.verified.txt#L1-L7' title='Snippet source file'>snippet source</a> | <a href='#snippet-Tests.LoggingTyped.verified.txt' title='Start of snippet'>anchor</a>}

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Log designed by Ben Davis from The Noun Project.