为 Cosmos 客户端编写单元测试时出错（无法将 List<model> 转换为 Task<FeedResponse<model>>）答案

【问题标题】：Error while writing Unit test for Cosmos Client ( Can not Convert List<model> to Task<FeedResponse<model>> )为 Cosmos 客户端编写单元测试时出错（无法将 List<model> 转换为 Task<FeedResponse<model>>）
【发布时间】：2020-06-12 08:10:38
【问题描述】：

包装-

Microsoft.Azure.Cosmos.Client，版本=3.8.0.0 我试图模拟的方法是 -

public async Task LoadCollectionFromStorageAsync()
        {
            string query = "SELECT* FROM c";
            QueryDefinition queryDefinition = new QueryDefinition(query);

            FeedIterator<MyType> queryResultSetIterator = _client.GetContainer(_settings.CosmosDbDatabaseId, _settings.Table).GetItemQueryIterator<MyType>(queryDefinition);

            List<MyType> results = new List<MyType>();
            while (queryResultSetIterator.HasMoreResults)
            {
                results.AddRange(await queryResultSetIterator.ReadNextAsync());
            }
        }

下面是代码---我得到错误的地方----

Mock<CosmosClient> _mockClient = new Mock<CosmosClient>();
Mock<Container>() _mockContainer = new Mock<Container>();

List<MyType> model =  new List<MyType>();
{
  PartitonKey= "p1",
  Name = "name1"
};

_mockClient.Setup(_ => _.GetContainer(It.IsAny<string>(), It.IsAny<string>())).Returns(_mockContainer.Object);

_mockContainer.Setup(_ => _.GetItemQueryIterator<MyType>(It.IsAny<string>(), null, null).ReadNextAsync(It.IsAny<CancellationToken>()))
            .Returns(model);

【问题讨论】：

请分享完整的代码示例
@PavelAnikhouski 添加了我要模拟的方法。

标签： c# unit-testing nunit azure-cosmosdb moq

【解决方案1】：

您正在模拟返回 FeedIterator 的 GetItemQueryIterator，当调用 ReadNextAsync 时，它返回 FeedResponse<T>，而不是 List<T>。

你可以这样做：

[TestMethod]
public async Task MyTestMethod()
{
    List<MyType> results =  new List<MyType>();
    {
      PartitonKey= "p1",
      Name = "name1"
    };

    Mock<FeedResponse<MyType>> mockedResponse = new Mock<FeedResponse<MyType>>();
    mockedResponse.Setup(r => r.Resource).Returns(results);
    Mock<FeedIterator<MyType>> mockedIterator = new Mock<FeedIterator<MyType>>();
    mockedIterator.Setup(q => q.ReadNextAsync(It.IsAny<CancellationToken>()))
        .ReturnsAsync(() => mockedResponse.Object);
    mockedIterator.SetupSequence(q => q.HasMoreResults)
        .Returns(true)
        .Returns(false);

    while (mockedIterator.Object.HasMoreResults)
    {
        FeedResponse<MyType> feedresponse = await mockedIterator.Object.ReadNextAsync();
        Assert.AreEqual(results, feedresponse.Resource);
    }

    Mock.Get(mockedIterator.Object)
        .Verify(q => q.ReadNextAsync(It.IsAny<CancellationToken>()), Times.Once);
    Mock.Get(mockedIterator.Object)
        .Verify(q => q.HasMoreResults, Times.Exactly(2));
    Mock.Get(mockedResponse.Object)
        .Verify(r => r.Resource, Times.Once);
}

【讨论】：