使用最小起订量测试Polly重试策略 [英] Testing Polly retry policy with moq

问题描述

我正在尝试为波莉编写单元测试，但是看起来返回值已被缓存.

I'm trying to write a unit test for polly, but it looks like the return is cached.

PostAsyncWithRetry方法:

Method PostAsyncWithRetry:

using Polly;
using System;
using System.Diagnostics;
using System.Net.Cache;
using System.Net.Http;
public class RetryClient
{
    private HttpClient httpClient = new HttpClient(new WebRequestHandler()
    { CachePolicy = new HttpRequestCachePolicy(HttpRequestCacheLevel.NoCacheNoStore) });

    public HttpResponseMessage PostAsyncWithRetry(
        String url,
        String path,
        StringContent httpContent)
    {
        httpClient.BaseAddress = new Uri(url);

        var retryPolicy =
            Policy.Handle<HttpRequestException>()
            .OrResult<HttpResponseMessage>(r => !r.IsSuccessStatusCode)
            .RetryAsync(3, (exception, retryCount, context) =>
            {
                Debug.WriteLine("RetryCount: {0}", retryCount);
            });

        var response = retryPolicy.ExecuteAsync(async () =>
        {
            return await httpClient.PostAsync(path, httpContent);
        }
        );

        return response.Result;
    }
}

测试:

[TestFixture]
class Test
{
    private HttpClient mockHTTPClient;
    private Mock<WebRequestHandler> mockHttpMessageHandler;
    private RetryClient testInstance;

    private const String URL = "https://aaa.com";
    private const String PATH = "/path";
    private const String EXPECTED_STRING_CONTENT = "Some return text";

    [SetUp]
    public void SetUp()
    {
        testInstance = new RetryClient();
        mockHttpMessageHandler = new Mock<WebRequestHandler>();
        mockHttpMessageHandler.Object.CachePolicy = new HttpRequestCachePolicy(HttpRequestCacheLevel.NoCacheNoStore);

        mockHTTPClient = new HttpClient(mockHttpMessageHandler.Object);

        var type = typeof(RetryClient);
        var fields = type.GetFields(BindingFlags.NonPublic | BindingFlags.Instance);
        fields[0].SetValue(testInstance, mockHTTPClient);
    }

    [Test]
    public void TestMEEEE()
    {
        var responses = new Queue<Task<HttpResponseMessage>>();
        responses.Enqueue(Task.FromResult(new HttpResponseMessage
        {
            StatusCode = HttpStatusCode.NotFound,
            Content = new StringContent(EXPECTED_STRING_CONTENT)
        }));
        responses.Enqueue(Task.FromResult(new HttpResponseMessage
        {
            StatusCode = HttpStatusCode.OK,
            Content = new StringContent(EXPECTED_STRING_CONTENT)
        }));

        var postContent = new StringContent(EXPECTED_STRING_CONTENT);
        mockHttpMessageHandler.Protected()
           .Setup<Task>("SendAsync", ItExpr.IsAny<HttpRequestMessage>(), ItExpr.IsAny<CancellationToken>())
           .Returns(responses.Dequeue());

        var response = testInstance.PostAsyncWithRetry(
            URL, PATH, postContent);

        mockHttpMessageHandler.Verify();
        Assert.AreEqual(responses.Count, 0, "didn't dequeue");
        Assert.AreEqual(HttpStatusCode.OK, response.StatusCode, "Incorrect status code");
    }

}

不知道为什么，但是看起来响应队列只被出队一次，这使我相信响应正在被缓存.有谁知道谁在缓存响应，以及如何禁用它?

Not sure why, but it looks like the responses queue is only being Dequeue once, this leads me to believe the response is being cache. Does anyone know who is caching the response, and how do I disable it?

预先感谢一堆！

推荐答案

我知道了.它与缓存无关.在模拟设置期间，它将出队值存储为返回值，而不是每次都调用它. 将其更改为()=>响应.Dequeue()现在可以正常工作.

I figured it out. It has nothing to do with caching. During the mock setup, it stores the Dequeue value as a return instead of invoking it every time. Changing it to () => responses.Dequeue() works now.

谢谢你们！

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