aspnetcore/src/Middleware/HttpLogging/test/HttpLoggingMiddlewareTests.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.IO;
using System.Text;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Testing;
using Microsoft.Extensions.Options;
using Microsoft.Net.Http.Headers;
using Microsoft.Extensions.Logging;
using Moq;
using Xunit;

namespace Microsoft.AspNetCore.HttpLogging
{
    public class HttpLoggingMiddlewareTests : LoggedTest
    {
        public static TheoryData BodyData
        {
            get
            {
                var variations = new TheoryData<string>();
                variations.Add("Hello World");
                variations.Add(new string('a', 4097));
                variations.Add(new string('b', 10000));
                variations.Add(new string('あ', 10000));
                return variations;
            }
        }

        [Fact]
        public void Ctor_ThrowsExceptionsWhenNullArgs()
        {
            Assert.Throws<ArgumentNullException>(() => new HttpLoggingMiddleware(
                null,
                CreateOptionsAccessor(),
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>()));

            Assert.Throws<ArgumentNullException>(() => new HttpLoggingMiddleware(c =>
            {
                return Task.CompletedTask;
            },
            null,
            LoggerFactory.CreateLogger<HttpLoggingMiddleware>()));

            Assert.Throws<ArgumentNullException>(() => new HttpLoggingMiddleware(c =>
            {
                return Task.CompletedTask;
            },
            CreateOptionsAccessor(),
            null));
        }

        [Fact]
        public async Task NoopWhenLoggingDisabled()
        {
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.None;

            var middleware = new HttpLoggingMiddleware(
                c =>
                {
                    c.Response.StatusCode = 200;
                    return Task.CompletedTask;
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();
            httpContext.Request.Protocol = "HTTP/1.0";
            httpContext.Request.Method = "GET";
            httpContext.Request.Scheme = "http";
            httpContext.Request.Path = new PathString("/foo");
            httpContext.Request.PathBase = new PathString("/foo");
            httpContext.Request.QueryString = new QueryString("?foo");
            httpContext.Request.Headers["Connection"] = "keep-alive";
            httpContext.Request.ContentType = "text/plain";
            httpContext.Request.Body = new MemoryStream(Encoding.UTF8.GetBytes("test"));

            await middleware.Invoke(httpContext);

            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Protocol: HTTP/1.0"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Method: GET"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Scheme: http"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Path: /foo"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("PathBase: /foo"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("QueryString: ?foo"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Connection: keep-alive"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Body: test"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("StatusCode: 200"));
        }

        [Fact]
        public async Task DefaultRequestInfoOnlyHeadersAndRequestInfo()
        {
            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    var arr = new byte[4096];
                    while (true)
                    {
                        var res = await c.Request.Body.ReadAsync(arr);
                        if (res == 0)
                        {
                            break;
                        }
                    }
                },
                CreateOptionsAccessor(),
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();
            httpContext.Request.Protocol = "HTTP/1.0";
            httpContext.Request.Method = "GET";
            httpContext.Request.Scheme = "http";
            httpContext.Request.Path = new PathString("/foo");
            httpContext.Request.PathBase = new PathString("/foo");
            httpContext.Request.Headers["Connection"] = "keep-alive";
            httpContext.Request.ContentType = "text/plain";
            httpContext.Request.Body = new MemoryStream(Encoding.UTF8.GetBytes("test"));

            await middleware.Invoke(httpContext);
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Protocol: HTTP/1.0"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Method: GET"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Scheme: http"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Path: /foo"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("PathBase: /foo"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Connection: keep-alive"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Body: test"));
        }

        [Fact]
        public async Task RequestLogsAllRequestInfo()
        {
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.Request;
            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    var arr = new byte[4096];
                    while (true)
                    {
                        var res = await c.Request.Body.ReadAsync(arr);
                        if (res == 0)
                        {
                            break;
                        }
                    }
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();
            httpContext.Request.Protocol = "HTTP/1.0";
            httpContext.Request.Method = "GET";
            httpContext.Request.Scheme = "http";
            httpContext.Request.Path = new PathString("/foo");
            httpContext.Request.PathBase = new PathString("/foo");
            httpContext.Request.Headers["Connection"] = "keep-alive";
            httpContext.Request.ContentType = "text/plain";
            httpContext.Request.Body = new MemoryStream(Encoding.UTF8.GetBytes("test"));

            await middleware.Invoke(httpContext);
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Protocol: HTTP/1.0"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Method: GET"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Scheme: http"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Path: /foo"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("PathBase: /foo"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Connection: keep-alive"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Body: test"));
        }

        [Fact]
        public async Task RequestPropertiesLogs()
        {
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.RequestProperties;
            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    var arr = new byte[4096];
                    while (true)
                    {
                        var res = await c.Request.Body.ReadAsync(arr);
                        if (res == 0)
                        {
                            break;
                        }
                    }
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();
            httpContext.Request.Protocol = "HTTP/1.0";
            httpContext.Request.Method = "GET";
            httpContext.Request.Scheme = "http";
            httpContext.Request.Path = new PathString("/foo");
            httpContext.Request.PathBase = new PathString("/foo");
            httpContext.Request.Headers["Connection"] = "keep-alive";
            httpContext.Request.ContentType = "text/plain";
            httpContext.Request.Body = new MemoryStream(Encoding.UTF8.GetBytes("test"));

            await middleware.Invoke(httpContext);
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Protocol: HTTP/1.0"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Method: GET"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Scheme: http"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Path: /foo"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("PathBase: /foo"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Connection: keep-alive"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Body: test"));
        }

        [Fact]
        public async Task RequestHeadersLogs()
        {
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.RequestHeaders;
            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    var arr = new byte[4096];
                    while (true)
                    {
                        var res = await c.Request.Body.ReadAsync(arr);
                        if (res == 0)
                        {
                            break;
                        }
                    }
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();
            httpContext.Request.Protocol = "HTTP/1.0";
            httpContext.Request.Method = "GET";
            httpContext.Request.Scheme = "http";
            httpContext.Request.Path = new PathString("/foo");
            httpContext.Request.PathBase = new PathString("/foo");
            httpContext.Request.QueryString = new QueryString("?foo");
            httpContext.Request.Headers["Connection"] = "keep-alive";
            httpContext.Request.ContentType = "text/plain";
            httpContext.Request.Body = new MemoryStream(Encoding.UTF8.GetBytes("test"));

            await middleware.Invoke(httpContext);
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Protocol: HTTP/1.0"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Method: GET"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Scheme: http"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Path: /foo"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("PathBase: /foo"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("QueryString: ?foo"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Connection: keep-alive"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Body: test"));
        }

        [Fact]
        public async Task UnknownRequestHeadersRedacted()
        {
            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    var arr = new byte[4096];
                    while (true)
                    {
                        var res = await c.Request.Body.ReadAsync(arr);
                        if (res == 0)
                        {
                            break;
                        }
                    }
                },
                CreateOptionsAccessor(),
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();

            httpContext.Request.Headers["foo"] = "bar";

            await middleware.Invoke(httpContext);
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("foo: [Redacted]"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("foo: bar"));
        }

        [Fact]
        public async Task CanConfigureRequestAllowList()
        {
            var options = CreateOptionsAccessor();
            options.CurrentValue.RequestHeaders.Clear();
            options.CurrentValue.RequestHeaders.Add("foo");
            var middleware = new HttpLoggingMiddleware(
                 c =>
                 {
                     return Task.CompletedTask;
                 },
                 options,
                 LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();

            // Header on the default allow list.
            httpContext.Request.Headers["Connection"] = "keep-alive";

            httpContext.Request.Headers["foo"] = "bar";

            await middleware.Invoke(httpContext);
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("foo: bar"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("foo: [Redacted]"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Connection: [Redacted]"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Connection: keep-alive"));
        }

        [Theory]
        [MemberData(nameof(BodyData))]
        public async Task RequestBodyReadingWorks(string expected)
        {
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.RequestBody;

            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    var arr = new byte[4096];
                    while (true)
                    {
                        var res = await c.Request.Body.ReadAsync(arr);
                        if (res == 0)
                        {
                            break;
                        }
                    }
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();
            httpContext.Request.ContentType = "text/plain";
            httpContext.Request.Body = new MemoryStream(Encoding.UTF8.GetBytes(expected));

            await middleware.Invoke(httpContext);

            Assert.Contains(TestSink.Writes, w => w.Message.Contains(expected));
        }

        [Fact]
        public async Task RequestBodyReadingLimitLongCharactersWorks()
        {
            var input = string.Concat(new string('あ', 5));
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.RequestBody;
            options.CurrentValue.RequestBodyLogLimit = 4;

            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    var arr = new byte[4096];
                    var count = 0;
                    while (true)
                    {
                        var res = await c.Request.Body.ReadAsync(arr);
                        if (res == 0)
                        {
                            break;
                        }
                        count += res;
                    }

                    Assert.Equal(15, count);
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();
            httpContext.Request.ContentType = "text/plain";
            httpContext.Request.Body = new MemoryStream(Encoding.UTF8.GetBytes(input));

            await middleware.Invoke(httpContext);
            var expected = input.Substring(0, options.CurrentValue.RequestBodyLogLimit / 3);

            Assert.Contains(TestSink.Writes, w => w.Message.Equals("RequestBody: " + expected));
        }

        [Fact]
        public async Task RequestBodyReadingLimitWorks()
        {
            var input = string.Concat(new string('a', 60000), new string('b', 3000));
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.RequestBody;

            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    var arr = new byte[4096];
                    var count = 0;
                    while (true)
                    {
                        var res = await c.Request.Body.ReadAsync(arr);
                        if (res == 0)
                        {
                            break;
                        }
                        count += res;
                    }

                    Assert.Equal(63000, count);
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();
            httpContext.Request.ContentType = "text/plain";
            httpContext.Request.Body = new MemoryStream(Encoding.UTF8.GetBytes(input));

            await middleware.Invoke(httpContext);
            var expected = input.Substring(0, options.CurrentValue.ResponseBodyLogLimit);

            Assert.Contains(TestSink.Writes, w => w.Message.Equals("RequestBody: " + expected));
        }

        [Fact]
        public async Task PartialReadBodyStillLogs()
        {
            var input = string.Concat(new string('a', 60000), new string('b', 3000));
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.RequestBody;

            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    var arr = new byte[4096];
                    var res = await c.Request.Body.ReadAsync(arr);
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();
            httpContext.Request.ContentType = "text/plain";
            httpContext.Request.Body = new MemoryStream(Encoding.UTF8.GetBytes(input));

            await middleware.Invoke(httpContext);
            var expected = input.Substring(0, 4096);

            Assert.Contains(TestSink.Writes, w => w.Message.Equals("RequestBody: " + expected));
        }

        [Theory]
        [InlineData("text/plain")]
        [InlineData("text/html")]
        [InlineData("application/json")]
        [InlineData("application/xml")]
        [InlineData("application/entity+json")]
        [InlineData("application/entity+xml")]
        public async Task VerifyDefaultMediaTypeHeaders(string contentType)
        {
            // media headers that should work.
            var expected = new string('a', 1000);
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.RequestBody;

            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    var arr = new byte[4096];
                    while (true)
                    {
                        var res = await c.Request.Body.ReadAsync(arr);
                        if (res == 0)
                        {
                            break;
                        }
                    }
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();
            httpContext.Request.ContentType = contentType;
            httpContext.Request.Body = new MemoryStream(Encoding.UTF8.GetBytes(expected));

            await middleware.Invoke(httpContext);

            Assert.Contains(TestSink.Writes, w => w.Message.Contains(expected));
        }

        [Theory]
        [InlineData("application/invalid")]
        [InlineData("multipart/form-data")]
        public async Task RejectedContentTypes(string contentType)
        {
            // media headers that should work.
            var expected = new string('a', 1000);
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.RequestBody;

            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    var arr = new byte[4096];
                    var count = 0;

                    while (true)
                    {
                        var res = await c.Request.Body.ReadAsync(arr);
                        if (res == 0)
                        {
                            break;
                        }
                        count += res;
                    }

                    Assert.Equal(1000, count);
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();
            httpContext.Request.ContentType = contentType;
            httpContext.Request.Body = new MemoryStream(Encoding.UTF8.GetBytes(expected));

            await middleware.Invoke(httpContext);

            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains(expected));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Unrecognized Content-Type for body."));
        }

        [Fact]
        public async Task DifferentEncodingsWork()
        {
            var encoding = Encoding.Unicode;
            var expected = new string('a', 1000);
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.RequestBody;
            options.CurrentValue.MediaTypeOptions.Clear();
            options.CurrentValue.MediaTypeOptions.AddText("text/plain", encoding);

            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    var arr = new byte[4096];
                    var count = 0;
                    while (true)
                    {
                        var res = await c.Request.Body.ReadAsync(arr);
                        if (res == 0)
                        {
                            break;
                        }
                        count += res;
                    }

                    Assert.Equal(2000, count);
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();
            httpContext.Request.ContentType = "text/plain";
            httpContext.Request.Body = new MemoryStream(encoding.GetBytes(expected));

            await middleware.Invoke(httpContext);

            Assert.Contains(TestSink.Writes, w => w.Message.Contains(expected));
        }

        [Fact]
        public async Task DefaultResponseInfoOnlyHeadersAndRequestInfo()
        {
            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    c.Response.StatusCode = 200;
                    c.Response.Headers[HeaderNames.TransferEncoding] = "test";
                    c.Response.ContentType = "text/plain";
                    await c.Response.WriteAsync("test");
                },
                CreateOptionsAccessor(),
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();

            await middleware.Invoke(httpContext);
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("StatusCode: 200"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Transfer-Encoding: test"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Body: test"));
        }

        [Fact]
        public async Task ResponseInfoLogsAll()
        {
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.Response;

            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    c.Response.StatusCode = 200;
                    c.Response.Headers[HeaderNames.TransferEncoding] = "test";
                    c.Response.ContentType = "text/plain";
                    await c.Response.WriteAsync("test");
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();

            await middleware.Invoke(httpContext);
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("StatusCode: 200"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Transfer-Encoding: test"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Body: test"));
        }


        [Fact]
        public async Task StatusCodeLogs()
        {
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.ResponseStatusCode;

            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    c.Response.StatusCode = 200;
                    c.Response.Headers["Server"] = "Kestrel";
                    c.Response.ContentType = "text/plain";
                    await c.Response.WriteAsync("test");
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();

            await middleware.Invoke(httpContext);
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("StatusCode: 200"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Server: Kestrel"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Body: test"));
        }

        [Fact]
        public async Task ResponseHeadersLogs()
        {
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.ResponseHeaders;

            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    c.Response.StatusCode = 200;
                    c.Response.Headers[HeaderNames.TransferEncoding] = "test";
                    c.Response.ContentType = "text/plain";
                    await c.Response.WriteAsync("test");
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();

            await middleware.Invoke(httpContext);
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("StatusCode: 200"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Transfer-Encoding: test"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Body: test"));
        }

        [Fact]
        public async Task ResponseHeadersRedacted()
        {
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.ResponseHeaders;

            var middleware = new HttpLoggingMiddleware(
                c =>
                {
                    c.Response.Headers["Test"] = "Kestrel";
                    return Task.CompletedTask;
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();

            await middleware.Invoke(httpContext);
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Test: [Redacted]"));
        }

        [Fact]
        public async Task AllowedResponseHeadersModify()
        {
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.ResponseHeaders;
            options.CurrentValue.ResponseHeaders.Clear();
            options.CurrentValue.ResponseHeaders.Add("Test");

            var middleware = new HttpLoggingMiddleware(
                c =>
                {
                    c.Response.Headers["Test"] = "Kestrel";
                    c.Response.Headers["Server"] = "Kestrel";
                    return Task.CompletedTask;
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();

            await middleware.Invoke(httpContext);
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Test: Kestrel"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Server: [Redacted]"));
        }

        [Theory]
        [MemberData(nameof(BodyData))]
        public async Task ResponseBodyWritingWorks(string expected)
        {
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.ResponseBody;
            var middleware = new HttpLoggingMiddleware(
                c =>
                {
                    c.Response.ContentType = "text/plain";
                    return c.Response.WriteAsync(expected);
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();

            await middleware.Invoke(httpContext);

            Assert.Contains(TestSink.Writes, w => w.Message.Contains(expected));
        }

        [Fact]
        public async Task ResponseBodyWritingLimitWorks()
        {
            var input = string.Concat(new string('a', 30000), new string('b', 3000));
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.ResponseBody;
            var middleware = new HttpLoggingMiddleware(
                c =>
                {
                    c.Response.ContentType = "text/plain";
                    return c.Response.WriteAsync(input);
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();

            await middleware.Invoke(httpContext);

            var expected = input.Substring(0, options.CurrentValue.ResponseBodyLogLimit);
            Assert.Contains(TestSink.Writes, w => w.Message.Contains(expected));
        }

        [Fact]
        public async Task FirstWriteResponseHeadersLogged()
        {
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.Response;

            var writtenHeaders = new TaskCompletionSource<object>();
            var letBodyFinish = new TaskCompletionSource<object>();

            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    c.Response.StatusCode = 200;
                    c.Response.Headers[HeaderNames.TransferEncoding] = "test";
                    c.Response.ContentType = "text/plain";
                    await c.Response.WriteAsync("test");
                    writtenHeaders.SetResult(null);
                    await letBodyFinish.Task;
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();

            var middlewareTask = middleware.Invoke(httpContext);

            await writtenHeaders.Task;

            Assert.Contains(TestSink.Writes, w => w.Message.Contains("StatusCode: 200"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Transfer-Encoding: test"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Body: test"));

            letBodyFinish.SetResult(null);

            await middlewareTask;

            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Body: test"));
        }

        [Fact]
        public async Task StartAsyncResponseHeadersLogged()
        {
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.Response;

            var writtenHeaders = new TaskCompletionSource<object>();
            var letBodyFinish = new TaskCompletionSource<object>();

            var middleware = new HttpLoggingMiddleware(
                async c =>
                {
                    c.Response.StatusCode = 200;
                    c.Response.Headers[HeaderNames.TransferEncoding] = "test";
                    c.Response.ContentType = "text/plain";
                    await c.Response.StartAsync();
                    writtenHeaders.SetResult(null);
                    await letBodyFinish.Task;
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();

            var middlewareTask = middleware.Invoke(httpContext);

            await writtenHeaders.Task;

            Assert.Contains(TestSink.Writes, w => w.Message.Contains("StatusCode: 200"));
            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Transfer-Encoding: test"));
            Assert.DoesNotContain(TestSink.Writes, w => w.Message.Contains("Body: test"));

            letBodyFinish.SetResult(null);

            await middlewareTask;
        }

        [Fact]
        public async Task UnrecognizedMediaType()
        {
            var expected = "Hello world";
            var options = CreateOptionsAccessor();
            options.CurrentValue.LoggingFields = HttpLoggingFields.ResponseBody;
            var middleware = new HttpLoggingMiddleware(
                c =>
                {
                    c.Response.ContentType = "foo/*";
                    return c.Response.WriteAsync(expected);
                },
                options,
                LoggerFactory.CreateLogger<HttpLoggingMiddleware>());

            var httpContext = new DefaultHttpContext();

            await middleware.Invoke(httpContext);

            Assert.Contains(TestSink.Writes, w => w.Message.Contains("Unrecognized Content-Type for body."));
        }

        private IOptionsMonitor<HttpLoggingOptions> CreateOptionsAccessor()
        {
            var options = new HttpLoggingOptions();
            var optionsAccessor = Mock.Of<IOptionsMonitor<HttpLoggingOptions>>(o => o.CurrentValue == options);
            return optionsAccessor;
        }
    }
}