我有模拟 http 客户端的功能：

private void MockClient(HttpStatusCode status,HttpContent content = null)
 {
   _client
     .Setup(m => m.Get(It.IsAny<string>(),It.IsAny<CancellationToken>()))
     .Returns(() => Task.FromResult(new HttpResponseMessage {StatusCode = status,Content = content})).Verifiable();
 }

我使用它进行这样的测试：

        [Fact]
        public async void Get_SerializerFailure_Throws()
        {
            var content = new MemoryStream(new byte[5]);
            MockClient(HttpStatusCode.OK,new StreamContent(content));

            _jsonSerializer.Setup(x => x.DeserializeFromStream<Dto>(It.IsAny<Stream>())).Throws<JsonReaderException>();
            await Assert.ThrowsAsync<JsonReaderException>(() => _sut.GetallAsync());
        }

这里出现错误：

 typeof(System.ObjectDisposedException): Cannot access a disposed object.
Object name: 'System.Net.Http.StreamContent'.

但是，如果我像这样直接在测试中模拟客户端，它可以工作并且不会抛出此错误：

        [Fact]
        public async void Get_ProtobufSerializerFailure_Throws()
        {
            var content = new MemoryStream(new byte[5]);
            _client
                .Setup(m => m.Get(It.IsAny<string>(),It.IsAny<CancellationToken>()))
                .Returns(() => Task.FromResult(new HttpResponseMessage {StatusCode = HttpStatusCode.OK,Content = new StreamContent(content)})).Verifiable();


            _protobufSerializer.Setup(x => x.DeserializeFromStream<Dto>(It.IsAny<Stream>())).Throws<JsonReaderException>();
            await Assert.ThrowsAsync<JsonReaderException>(() => _sut.GetallAsync());
        }

我不明白这里有什么区别，为什么一种方法有效而另一种方法无效，以及如何修复我的模拟方法。

我正在测试这些方法：

private async Task<Object> GetLatest()
        {
            using (var response = await _client.Get($"{_serviceUrl}",CancellationToken.None))
            using (var stream = await response.Content.ReadAsStreamAsync())
            {
                return _jsonSerializer.DeserializeFromStream<Objects>(stream)?.Items.Last();
            }
        }

        public async Task<IReadOnlyList<(ulong key,Dto item)>> GetallAsync()
        {
            var latest = await GetLatest();

            using (var response = await _client.Get(url,CancellationToken.None))
            using (var stream = await response.Content.ReadAsStreamAsync())
            using (var decompressionStream = new GZipStream(stream,Compressionmode.Decompress))
            {
                var result = _protobufSerializer.DeserializeFromStream<Dto>(decompressionStream);
                return result.ToList();
            }
        }