public async Task Should_honour_cancellation_even_if_prior_execution_has_cached()
{
const string valueToReturn = "valueToReturn";
const string executionKey = "SomeExecutionKey";
CachePolicy cache = Policy.CacheAsync(new StubCacheProvider(), TimeSpan.MaxValue);
CancellationTokenSource tokenSource = new CancellationTokenSource();
int delegateInvocations = 0;
Func <CancellationToken, Task <string> > func = async ct =>
{
// delegate does not observe cancellation token; test is whether CacheEngine does.
delegateInvocations++;
await TaskHelper.EmptyTask.ConfigureAwait(false);
return(valueToReturn);
};
(await cache.ExecuteAsync(func, new Context(executionKey), tokenSource.Token).ConfigureAwait(false)).Should().Be(valueToReturn);
delegateInvocations.Should().Be(1);
tokenSource.Cancel();
cache.Awaiting(policy => policy.ExecuteAsync(func, new Context(executionKey), tokenSource.Token))
.ShouldThrow <OperationCanceledException>();
delegateInvocations.Should().Be(1);
}
public async Task Should_honour_cancellation_during_delegate_execution_and_not_put_to_cache()
{
const string valueToReturn = "valueToReturn";
const string executionKey = "SomeExecutionKey";
IAsyncCacheProvider stubCacheProvider = new StubCacheProvider();
CachePolicy cache = Policy.CacheAsync(stubCacheProvider, TimeSpan.MaxValue);
CancellationTokenSource tokenSource = new CancellationTokenSource();
Func <CancellationToken, Task <string> > func = async ct =>
{
tokenSource.Cancel(); // simulate cancellation raised during delegate execution
ct.ThrowIfCancellationRequested();
await TaskHelper.EmptyTask.ConfigureAwait(false);
return(valueToReturn);
};
cache.Awaiting(policy => policy.ExecuteAsync(func, new Context(executionKey), tokenSource.Token))
.ShouldThrow <OperationCanceledException>();
((string)await stubCacheProvider.GetAsync(executionKey, CancellationToken.None, false).ConfigureAwait(false)).Should().BeNull();
}