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ILogger Verification with Moq
using Microsoft.Extensions.Logging;
using Moq;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
// More detailed samples here:
// https://github.com/MelbourneDeveloper/RestClient.Net/blob/79cca66e02f83a1043c44f215d374139f40f8c12/src/RestClient.Net.UnitTests/UnitTests.cs#L758
namespace RestClient.Net.UnitTests
{
public static class LogCheckExtensions
{
/// <summary>
/// Verify that the log was called and get access to check the log arguments
/// </summary>
public static void VerifyLog<T, TException>(
this Mock<ILogger<T>> loggerMock,
Expression<Func<object, Type, bool>> match,
LogLevel logLevel,
int times) where TException : Exception
{
if (loggerMock == null) throw new ArgumentNullException(nameof(loggerMock));
loggerMock.Verify
(
l => l.Log
(
//Check the severity level
logLevel,
//This may or may not be relevant to your scenario
//If you need to check this, add a parameter for it
It.IsAny<EventId>(),
//This is the magical Moq code that exposes internal log processing from the extension methods
It.Is<It.IsAnyType>(match),
//Confirm the exception type
It.IsAny<TException>(),
//Accept any valid Func here. The Func is specified by the extension methods
(Func<It.IsAnyType, Exception, string>)It.IsAny<object>()
),
//Make sure the message was logged the correct number of times
Times.Exactly(times)
);
}
/// <summary>
/// Verify that the log was called and get access to check the log arguments
/// </summary>
public static void VerifyLog<T>(
this Mock<ILogger<T>> loggerMock,
Expression<Func<object, Type, bool>> match,
LogLevel logLevel,
int times)
=> VerifyLog<T, Exception>(loggerMock, match, logLevel, times);
/// <summary>
/// Check whether or not the log arguments match the expected result
/// </summary>
public static bool CheckValue<T>(this object state, string key, T expectedValue)
=> CheckValue<T>(state, key, (actualValue)
=> (actualValue == null && expectedValue == null) || (actualValue != null && actualValue.Equals(expectedValue)));
/// <summary>
/// Check whether or not the log arguments match the expected result
/// </summary>
public static bool CheckValue<T>(this object state, string key, Func<T, bool> compare)
{
if (compare == null) throw new ArgumentNullException(nameof(compare));
var exists = state.GetValue<T>(key, out var actualValue);
return exists && compare(actualValue);
}
#pragma warning disable CA1021 // Avoid out parameters
public static bool GetValue<T>(this object state, string key, out T value)
#pragma warning restore CA1021 // Avoid out parameters
{
var keyValuePairList = (IReadOnlyList<KeyValuePair<string, object>>)state;
var keyValuePair = keyValuePairList.FirstOrDefault(kvp => string.Compare(kvp.Key, key, StringComparison.Ordinal) == 0);
value = (T)keyValuePair.Value;
return keyValuePair.Key != null;
}
}
}
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