Getting Started

This guide will help you quickly get up and running with Wolfgang.Extensions.Logging.InMemoryLogger.

Prerequisites

  • The .NET 10.0 SDK is required to build the highest TFM.
  • Building the net462 target additionally requires the .NET Framework 4.6.2 reference assemblies / targeting pack (typically installed via Visual Studio's ".NET desktop development" workload on Windows; the SDK alone does not include them, and net462 builds are Windows-only).
  • The netstandard2.0, netstandard2.1, and net8.0 targets build with the .NET 10 SDK alone on any OS.

The library ships against net462, netstandard2.0, netstandard2.1, net8.0, and net10.0.

Installation

Via NuGet Package Manager

dotnet add package Wolfgang.Extensions.Logging.InMemoryLogger

Via Package Manager Console

Install-Package Wolfgang.Extensions.Logging.InMemoryLogger

Quick Start

Construct an InMemoryLogger<T> and inject it wherever an ILogger<T> is expected:

using Microsoft.Extensions.Logging;
using Wolfgang.Extensions.Logging.InMemoryLogger;

var logger = new InMemoryLogger<MyService>(LogLevel.Information);

// Production code under test
var service = new MyService(logger);
service.DoWork();

// Assert what was logged
Assert.Single(logger.LogEntries);
Assert.Equal(LogLevel.Information, logger.LogEntries[0].LogLevel);

When you need a non-generic ILogger and want to control the category string directly:

var logger = new InMemoryLogger(
    category: "MyApp.MyComponent",
    minLogLevel: LogLevel.Warning,
    capacity: 32);

To register with the standard ILoggerFactory:

using var loggerFactory = LoggerFactory.Create(b => b.AddInMemoryLogger());
var logger = loggerFactory.CreateLogger<MyService>();

State passed to BeginScope is captured in the Scopes property:

using (logger.BeginScope(new { CorrelationId = "abc-123" }))
{
    logger.LogInformation("processing");
}

Assert.Single(logger.Scopes);

Next Steps

Common Issues

LogEntries is empty even though my code logged

The InMemoryLogger constructor takes a minLogLevel (defaults to LogLevel.Trace). Anything below that threshold is filtered before reaching LogEntries. If you constructed the logger with LogLevel.Warning and the code under test only emits Information, no entries are captured. Lower the threshold or check IsEnabled first.

Scopes is empty after BeginScope

The scope must be active while the log call runs — the using block has to wrap the Log* call, not just the BeginScope invocation. The library captures scope state when an entry is appended, not when the scope opens.

Enumerating LogEntries from another thread

LogEntries is safe to read while a producer thread is still appending — the underlying buffer is thread-safe, and the property returns an IReadOnlyList<LogEntry<object>> snapshot prefix. You do not need to lock or copy before asserting.

Additional Resources

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