RandomSkunk.Logging.Testing.Moq

Mock logger implementations for Moq and Microsoft.Extensions.Logging.

The Microsoft.Extensions.Logging.ILogger interface is difficult to mock - its Log method is generic, but the extension methods that call it (e.g. LogError) pass an internal type as the generic argument. This means there's no good way to know if most logging has taken place. This library makes it easy to do this kind of verification.

Usage

// Create a mock logger.
var mockLogger = new MockLogger();

// Do some logging.
mockLogger.Object.LogInformation("Hello, {who}!", "world");

// Verify that the logging occurred.
mockLogger.Verify(m => m.Log(
    LogLevel.Information,
    It.IsAny<EventId>(),
    "Hello, world!",
    null));

Verifying a method with four parameters (i.e. the Log method) can be a bit tedious. To lessen the tedium, the VerifyLog extension method is provided.

mockLogger.VerifyLog(
    log => log.AtInformation().WithMessage("Hello, world!").WithoutException());

Similarly, setting up the Log method (e.g. to set a callback method) can be tedious. The SetupLog extension method is provided to help:

mockLogger.SetupLog()
    .Callback<LogLevel, EventId, string, Exception>(
        (logLevel, eventId, message, exception) =>
        {
            // TODO: Handle the callback.
        });