I've worked with concurrency, but I don't know any good way to test it.
I would want to know if there is any way to "force" Tasks to execute in an specific order to simulate tests cases.
For example:
I have seen some people using custom TaskSchedulers. Does it make sense?
I had had that problem in several occurrences too. Eventually I have created a helper that can start a bunch of threads to execute concurrent actions. The helper provides synchronization primitives and logging mechanisms. Here is a code fragment from a unit test:
[Test] public void TwoCodeBlocksInParallelTest() { // This static method runs the provided Action delegates in parallel using threads CTestHelper.Run( c => { Thread.Sleep(1000); // Here should be the code to provide something CTestHelper.AddSequenceStep("Provide"); // We record a sequence step for the expectations after the test CTestHelper.SetEvent(); }, c => { CTestHelper.WaitEvent(); // We wait until we can consume what is provided CTestHelper.AddSequenceStep("Consume"); // We record a sequence step for the expectations after the test }, TimeSpan.FromSeconds(10)); // This is a timeout parameter, if the threads are deadlocked or take too long, the threads are terminated and a timeout exception is thrown // After Run() completes we can analyze if the recorded sequence steps are in the correct order Expect(CTestHelper.GetSequence(), Is.EqualTo(new[] { "Provide", "Consume" })); } It can be used to test client/server or synchronization in components or simply run a thread with a timeout. I'll continue to improve this in the next weeks. Here is the project page: Concurrency Testing Helper
This shouldn't be too difficult to simulate using tasks:
private async Task DoSomeAsyncOperation() { // This is just to simulate some work, // replace this with a usefull call to the server await Task.Delay(3000); } Now, lets consume it:
public async Task TestServerLoad() { var firstTaskCall = DoSomeAsyncOperation(); await Task.Delay(1000); // Lets assume it takes about a second to execute work agains't the server var secondCall = DoSomeAsyncOperation(); await Task.WhenAll(firstTaskCall, secondCall); // Wait till both complete } This is basic producer-consumer problem in concurrency. If you want to test that case, just put a Thread.Sleep(100) to server which part responds consumers. In that way, your server will have a delay before sending response. And you can Invoke service request simply creating new threads in a loop.
