aspnetcore/test/Microsoft.AspNetCore.DataProtection.Test/StringLoggerFactory.cs

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Globalization;
using System.Text;
using Microsoft.Extensions.Logging;

namespace Microsoft.AspNetCore.DataProtection
{
    internal sealed class StringLoggerFactory : ILoggerFactory
    {
        private readonly StringBuilder _log = new StringBuilder();

        public StringLoggerFactory(LogLevel logLevel)
        {
            MinimumLevel = logLevel;
        }

        public LogLevel MinimumLevel { get; set; }

        public void AddProvider(ILoggerProvider provider)
        {
            // no-op
        }

        public ILogger CreateLogger(string name)
        {
            return new StringLogger(name, this);
        }

        public void Dispose()
        {
        }

        public override string ToString()
        {
            return _log.ToString();
        }

        private sealed class StringLogger : ILogger
        {
            private readonly StringLoggerFactory _factory;
            private readonly string _name;

            public StringLogger(string name, StringLoggerFactory factory)
            {
                _name = name;
                _factory = factory;
            }

            public IDisposable BeginScope<TState>(TState state)
            {
                return new DummyDisposable();
            }

            public bool IsEnabled(LogLevel logLevel)
            {
                return (logLevel >= _factory.MinimumLevel);
            }

            public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)
            {
                string message = String.Format(CultureInfo.InvariantCulture,
                    "Provider: {0}" + Environment.NewLine +
                    "Log level: {1}" + Environment.NewLine +
                    "Event id: {2}" + Environment.NewLine +
                    "Exception: {3}" + Environment.NewLine +
                    "Message: {4}", _name, logLevel, eventId, exception?.ToString(), formatter(state, exception));
                _factory._log.AppendLine(message);
            }

            private sealed class DummyDisposable : IDisposable
            {
                public void Dispose()
                {
                    // no-op
                }
            }
        }
    }
}