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Easily check ILogger<T> interactions with ASP.NET Core Logging and Moq
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using Microsoft.Extensions.Logging; | |
using Moq; | |
using System; | |
using System.Collections.Generic; | |
using System.Linq; | |
using System.Threading.Tasks; | |
using Xunit; | |
namespace Knaap.Utilties | |
{ | |
public class SimpleLogCheck | |
{ | |
[Fact] | |
public void TestLog() | |
{ | |
var loggerMock = LoggerUtils.LoggerMock<SimpleLogCheck>(); | |
loggerMock.Object.LogInformation("test"); | |
loggerMock.VerifyLog(LogLevel.Information, "test"); | |
} | |
} | |
public static class LoggerUtils | |
{ | |
public static Mock<ILogger<T>> LoggerMock<T>() where T : class | |
{ | |
return new Mock<ILogger<T>>(); | |
} | |
/// <summary> | |
/// Returns an <pre>ILogger<T></pre> as used by the Microsoft.Logging framework. | |
/// You can use this for constructors that require an ILogger parameter. | |
/// </summary> | |
/// <typeparam name="T"></typeparam> | |
/// <returns></returns> | |
public static ILogger<T> Logger<T>() where T : class | |
{ | |
return LoggerMock<T>().Object; | |
} | |
public static void VerifyLog<T>(this Mock<ILogger<T>> loggerMock, LogLevel level, string message, string failMessage = null) | |
{ | |
loggerMock.VerifyLog(level, message, Times.Once(), failMessage); | |
} | |
public static void VerifyLog<T>(this Mock<ILogger<T>> loggerMock, LogLevel level, string message, Times times, string failMessage = null) | |
{ | |
loggerMock.Verify(l => l.Log<Object>(level, It.IsAny<EventId>(), It.Is<Object>(o => o.ToString() == message), null, It.IsAny<Func<Object, Exception, String>>()), times, failMessage); | |
} | |
} | |
} |
Didn't work for me
This worked for me. Notice that I decided to use Contains instead of equal but that should not affect the result. If something does not match starting from message text to signature it will say 0 occurences. I took me some time to find the solution.
loggerMock.Verify(
x => x.Log(
level,
It.IsAny<EventId>(),
It.Is<It.IsAnyType>((o, t) => o.ToString().Contains(message)),
It.IsAny<Exception>(),
(Func<It.IsAnyType, Exception, string>) It.IsAny<object>()),
times);
Thanks, @aperisic. Your solution works for .NET Core 3.1. The original solution worked for .NET Core 2.1 but failed after migration to v3.
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Didn't work for me
Moq.MockException :
Expected invocation on the mock once, but was 0 times: l => l.Log(LogLevel.Information, It.IsAny(), It.Is(o => o.ToString() == "test"), null, It.IsAny<Func<object, Exception, string>>())
Performed invocations:
Mock<ILogger:1> (l):
at Moq.Mock.Verify(Mock mock, LambdaExpression expression, Times times, String failMessage)
at Moq.Mock
1.Verify(Expression
1 expression, Times times, String failMessage)at CtCore.Email.Test.Common.Utils.LoggerUtils.VerifyLog[T](Mock`1 loggerMock, LogLevel level, String message, Times times, String failMessage) in D:\ct.git\secure-document-vault\ctcore-email\CtCore.Email.Test.Common\Utils\LoggerUtils.cs:line 31