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Add methods to copy CloudEvents to HttpResponse
One part of cloudevents#148 Signed-off-by: Jon Skeet <[email protected]>
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‎src/CloudNative.CloudEvents.AspNetCore/HttpResponseExtensions.cs

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// Copyright (c) Cloud Native Foundation.
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// Licensed under the Apache 2.0 license.
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// See LICENSE file in the project root for full license information.
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using CloudNative.CloudEvents.Core;
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using CloudNative.CloudEvents.Http;
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using Microsoft.AspNetCore.Http;
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using System;
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using System.Collections.Generic;
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using System.Net.Mime;
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using System.Text;
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using System.Threading.Tasks;
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namespace CloudNative.CloudEvents.AspNetCore
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{
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/// <summary>
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/// Extension methods to convert between HTTP responses and CloudEvents.
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/// </summary>
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public static class HttpResponseExtensions
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{
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/// <summary>
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/// Copies a <see cref="CloudEvent"/> into an <see cref="HttpResponse" />.
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/// </summary>
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/// <param name="cloudEvent">The CloudEvent to copy. Must not be null, and must be a valid CloudEvent.</param>
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/// <param name="destination">The response to copy the CloudEvent to. Must not be null.</param>
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/// <param name="contentMode">Content mode (structured or binary)</param>
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/// <param name="formatter">The formatter to use within the conversion. Must not be null.</param>
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/// <returns>A task representing the asynchronous operation.</returns>
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public static async Task CopyToHttpResponseAsync(this CloudEvent cloudEvent, HttpResponse destination,
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ContentMode contentMode, CloudEventFormatter formatter)
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{
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Validation.CheckCloudEventArgument(cloudEvent, nameof(cloudEvent));
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Validation.CheckNotNull(destination, nameof(destination));
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Validation.CheckNotNull(formatter, nameof(formatter));
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ReadOnlyMemory<byte> content;
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ContentType contentType;
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switch (contentMode)
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{
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case ContentMode.Structured:
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content = formatter.EncodeStructuredModeMessage(cloudEvent, out contentType);
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break;
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case ContentMode.Binary:
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content = formatter.EncodeBinaryModeEventData(cloudEvent);
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contentType = MimeUtilities.CreateContentTypeOrNull(cloudEvent.DataContentType);
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break;
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default:
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throw new ArgumentOutOfRangeException(nameof(contentMode), $"Unsupported content mode: {contentMode}");
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}
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if (contentType is object)
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{
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destination.ContentType = contentType.ToString();
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}
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else if (content.Length != 0)
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{
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throw new ArgumentException("The 'datacontenttype' attribute value must be specified", nameof(cloudEvent));
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}
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// Map headers in either mode.
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// Including the headers in structured mode is optional in the spec (as they're already within the body) but
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// can be useful.
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destination.Headers.Add(HttpUtilities.SpecVersionHttpHeader, HttpUtilities.EncodeHeaderValue(cloudEvent.SpecVersion.VersionId));
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foreach (var attributeAndValue in cloudEvent.GetPopulatedAttributes())
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{
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var attribute = attributeAndValue.Key;
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var value = attributeAndValue.Value;
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// The content type is already handled based on the content mode.
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if (attribute != cloudEvent.SpecVersion.DataContentTypeAttribute)
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{
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string headerValue = HttpUtilities.EncodeHeaderValue(attribute.Format(value));
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destination.Headers.Add(HttpUtilities.HttpHeaderPrefix + attribute.Name, headerValue);
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}
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}
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destination.ContentLength = content.Length;
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await BinaryDataUtilities.CopyToStreamAsync(content, destination.Body).ConfigureAwait(false);
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}
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/// <summary>
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/// Copies a <see cref="CloudEvent"/> batch into an <see cref="HttpResponse" />.
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/// </summary>
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/// <param name="cloudEvents">The CloudEvent batch to copy. Must not be null, and must be a valid CloudEvent.</param>
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/// <param name="destination">The response to copy the CloudEvent to. Must not be null.</param>
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/// <param name="formatter">The formatter to use within the conversion. Must not be null.</param>
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/// <returns>A task representing the asynchronous operation.</returns>
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public static async Task CopyToHttpResponseAsync(this IReadOnlyList<CloudEvent> cloudEvents,
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HttpResponse destination, CloudEventFormatter formatter)
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{
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Validation.CheckCloudEventBatchArgument(cloudEvents, nameof(cloudEvents));
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Validation.CheckNotNull(destination, nameof(destination));
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Validation.CheckNotNull(formatter, nameof(formatter));
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// TODO: Validate that all events in the batch have the same version?
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// See https://github.com/cloudevents/spec/issues/807
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ReadOnlyMemory<byte> content = formatter.EncodeBatchModeMessage(cloudEvents, out var contentType);
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destination.ContentType = contentType.ToString();
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destination.ContentLength = content.Length;
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await BinaryDataUtilities.CopyToStreamAsync(content, destination.Body).ConfigureAwait(false);
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}
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}
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}

‎test/CloudNative.CloudEvents.UnitTests/AspNetCore/HttpResponseExtensionsTest.cs

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// Copyright 2021 Cloud Native Foundation.
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// Licensed under the Apache 2.0 license.
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// See LICENSE file in the project root for full license information.
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using CloudNative.CloudEvents.Core;
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using CloudNative.CloudEvents.NewtonsoftJson;
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using Microsoft.AspNetCore.Http;
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using Microsoft.AspNetCore.Http.Internal;
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using System;
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using System.IO;
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using System.Net.Mime;
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using System.Text;
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using System.Threading.Tasks;
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using Xunit;
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using static CloudNative.CloudEvents.UnitTests.TestHelpers;
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namespace CloudNative.CloudEvents.AspNetCore.UnitTests
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{
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public class HttpResponseExtensionsTest
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{
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[Fact]
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public async Task CopyToHttpResponseAsync_BinaryMode()
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{
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var cloudEvent = new CloudEvent
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{
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Data = "plain text",
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DataContentType = "text/plain"
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}.PopulateRequiredAttributes();
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var formatter = new JsonEventFormatter();
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var response = CreateResponse();
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await cloudEvent.CopyToHttpResponseAsync(response, ContentMode.Binary, formatter);
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var content = GetContent(response);
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Assert.Equal("text/plain", response.ContentType);
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Assert.Equal("plain text", Encoding.UTF8.GetString(content.Span));
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Assert.Equal("1.0", response.Headers["ce-specversion"]);
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Assert.Equal(cloudEvent.Type, response.Headers["ce-type"]);
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Assert.Equal(cloudEvent.Id, response.Headers["ce-id"]);
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Assert.Equal(CloudEventAttributeType.UriReference.Format(cloudEvent.Source), response.Headers["ce-source"]);
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// There's no data content type header; the content type itself is used for that.
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Assert.False(response.Headers.ContainsKey("ce-datacontenttype"));
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}
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[Fact]
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public async Task CopyToHttpResponseAsync_ContentButNoContentType()
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{
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var cloudEvent = new CloudEvent
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{
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Data = "plain text",
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}.PopulateRequiredAttributes();
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var formatter = new JsonEventFormatter();
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var response = CreateResponse();
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await Assert.ThrowsAsync<ArgumentException>(() => cloudEvent.CopyToHttpResponseAsync(response, ContentMode.Binary, formatter));
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}
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[Fact]
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public async Task CopyToHttpResponseAsync_BadContentMode()
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{
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var cloudEvent = new CloudEvent().PopulateRequiredAttributes();
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var formatter = new JsonEventFormatter();
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var response = CreateResponse();
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await Assert.ThrowsAsync<ArgumentOutOfRangeException>(() => cloudEvent.CopyToHttpResponseAsync(response, (ContentMode)100, formatter));
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}
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[Fact]
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public async Task CopyToHttpResponseAsync_StructuredMode()
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{
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var cloudEvent = new CloudEvent
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{
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Data = "plain text",
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DataContentType = "text/plain"
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}.PopulateRequiredAttributes();
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var formatter = new JsonEventFormatter();
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var response = CreateResponse();
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await cloudEvent.CopyToHttpResponseAsync(response, ContentMode.Structured, formatter);
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var content = GetContent(response);
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Assert.Equal(MimeUtilities.MediaType + "+json; charset=utf-8", response.ContentType);
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var parsed = new JsonEventFormatter().DecodeStructuredModeMessage(content, new ContentType(response.ContentType), extensionAttributes: null);
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AssertCloudEventsEqual(cloudEvent, parsed);
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Assert.Equal(cloudEvent.Data, parsed.Data);
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// We populate headers even though we don't strictly need to; let's validate that.
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Assert.Equal("1.0", response.Headers["ce-specversion"]);
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Assert.Equal(cloudEvent.Type, response.Headers["ce-type"]);
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Assert.Equal(cloudEvent.Id, response.Headers["ce-id"]);
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Assert.Equal(CloudEventAttributeType.UriReference.Format(cloudEvent.Source), response.Headers["ce-source"]);
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// We don't populate the data content type header
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Assert.False(response.Headers.ContainsKey("ce-datacontenttype"));
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}
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[Fact]
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public async Task CopyToHttpResponseAsync_Batch()
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{
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var batch = CreateSampleBatch();
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var response = CreateResponse();
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await batch.CopyToHttpResponseAsync(response, new JsonEventFormatter());
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var content = GetContent(response);
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Assert.Equal(MimeUtilities.BatchMediaType + "+json; charset=utf-8", response.ContentType);
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var parsedBatch = new JsonEventFormatter().DecodeBatchModeMessage(content, new ContentType(response.ContentType), extensionAttributes: null);
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AssertBatchesEqual(batch, parsedBatch);
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}
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private static HttpResponse CreateResponse() => new DefaultHttpResponse(new DefaultHttpContext()) { Body = new MemoryStream() };
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private static ReadOnlyMemory<byte> GetContent(HttpResponse response)
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{
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response.Body.Position = 0;
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return BinaryDataUtilities.ToReadOnlyMemory(response.Body);
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}
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}
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}

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