我正在为我的代码编写单元测试,并且遇到了一个方法,在尝试创建队列和AddMessage到队列时会抛出StorageException。我想测试异常处理是否正常。为了做到这一点,我想到了为CloudQueue使用模拟,但后来发现这个类是密封的。有没有办法在不实际更改生产代码的情况下测试异常处理(或强制执行StorageException)?
答案 0 :(得分:6)
处理此问题的最简单方法是使用CloudQueueClient
附近的接口(这是@tyrion建议的),上面是.. ICloudQueue
的接口
public interface ICloudQueueClientWrapper
{
ICloudQueueWrapper GetQueueReference(string queueName);
}
// ----------------
public class CloudQueueClientWrapper : ICloudQueueClientWrapper
{
private readonly Lazy<CloudQueueClient> _cloudQueueClient;
public CloudQueueClientWrapper(string connectionStringName)
{
connectionStringName.ShouldNotBeNullOrWhiteSpace();
_cloudQueueClient = new Lazy<CloudQueueClient>(() =>
{
// We first need to connect to our Azure storage.
var storageConnectionString = CloudConfigurationManager.GetSetting(connectionStringName);
var storageAccount = CloudStorageAccount.Parse(storageConnectionString);
// Create the queue client.
return storageAccount.CreateCloudQueueClient();
});
}
public ICloudQueueWrapper GetQueueReference(string queueName)
{
queueName.ShouldNotBeNullOrWhiteSpace();
var cloudQueue = _cloudQueueClient.Value.GetQueueReference(queueName);
return new CloudQueueWrapper(cloudQueue);
}
// Add more methods here which are a one-to-one match against the underlying CQC.
}
这是第一个接口和包装器...并注意这会返回一个ICloudQueue
实例..所以现在让我们这样做......
public interface ICloudQueueWrapper
{
Task AddMessageAsync(CloudQueueMessage message);
}
public class CloudQueueWrapper : ICloudQueueWrapper
{
private readonly CloudQueue _cloudQueue;
public CloudQueueWrapper(CloudQueue cloudQueue)
{
cloudQueue.ShouldNotBeNull();
_cloudQueue = cloudQueue;
}
public async Task AddMessageAsync(CloudQueueMessage message)
{
message.ShouldNotBeNull();
await _cloudQueue.AddMessageAsync(message);
}
}
好的......所以现在让我们尝试在某些单元测试中使用它:)
[Theory]
[MemberData(nameof(StockIds))]
public async Task GivenSomeData_DoFooAsync_AddsDataToTheQueue(string[] stockIds)
{
// Arrange.
var cloudQueue = Mock.Of<ICloudQueueWrapper>();
var cloudQueueClient = Mock.Of<ICloudQueueClientWrapper>();
Mock.Get(cloudQueueClient).Setup(x => x.GetQueueReference(It.IsAny<string>()))
.Returns(cloudQueue);
var someService = new SomeService(cloudQueueClient);
// Act.
await someService.DoFooAsync(Session);
// Assert.
// Did we end up getting a reference to the queue?
Mock.Get(cloudQueueClient).Verify(x => x.GetQueueReference(It.IsAny<string>()), Times.Once);
// Did we end up adding something to the queue?
Mock.Get(cloudQueue).Verify(x => x.AddMessageAsync(It.IsAny<CloudQueueMessage>()), Times.Exactly(stockids.Length));
}
答案 1 :(得分:1)
我们使用Microsoft Fakes框架能够在过去对类似的Azure SDK类进行单元测试。预先有一点学习曲线,但效果很好。
答案 2 :(得分:0)
@ Pure.Krome的解决方案是实现此目标的好方法-我只想指出他实现CloudQueueClientWraper
的一个可能的问题:
public class CloudQueueClientWrapper : ICloudQueueClientWrapper
{
private readonly Lazy<CloudQueueClient> _cloudQueueClient;
public CloudQueueClientWrapper(string connectionStringName)
{
connectionStringName.ShouldNotBeNullOrWhiteSpace();
_cloudQueueClient = new Lazy<CloudQueueClient>(() =>
{
// We first need to connect to our Azure storage.
var storageConnectionString = CloudConfigurationManager.GetSetting(connectionStringName);
var storageAccount = CloudStorageAccount.Parse(storageConnectionString);
// Create the queue client.
return storageAccount.CreateCloudQueueClient();
});
}
public ICloudQueueWrapper GetQueueReference(string queueName)
{
queueName.ShouldNotBeNullOrWhiteSpace();
var cloudQueue = _cloudQueueClient.Value.GetQueueReference(queueName);
return new CloudQueueWrapper(cloudQueue);
}
// Add more methods here which are a one-to-one match against the underlying CQC.
}
Lazy<T>
缓存异常!因此,如果一个线程(或更确切地说是Task
)通过执行.Value
委托创建valueFactory
的尝试失败并带有Exception,则对.Value
的所有后续调用都将返回相同的结果例外。
docs说:
异常缓存使用工厂方法时,将缓存异常。也就是说,如果工厂方法在线程第一次尝试访问Lazy对象的Value属性时引发异常,则在以后的每次尝试中都会引发相同的异常。这样可以确保对Value属性的每次调用都产生相同的结果,并避免了如果不同的线程获得不同的结果可能会引起的细微错误。惰性代表实际的T,否则通常会在启动过程中在某个较早的时间点对其进行初始化。在此之前的故障通常是致命的。如果有可能发生可恢复的故障,我们建议您将重试逻辑构建到初始化例程(在本例中为factory方法)中,就像您不使用惰性初始化一样。
作为“解决方法”-放弃内置Lazy<T>
并实施您自己的。 @mariusGundersen
public class AtomicLazy<T>
{
private readonly Func<T> _factory;
private T _value;
private bool _initialized;
private object _lock;
public AtomicLazy(Func<T> factory)
{
_factory = factory;
}
public AtomicLazy(T value)
{
_value = value;
_initialized = true;
}
public T Value => LazyInitializer.EnsureInitialized(ref _value, ref _initialized, ref _lock, _factory);
}