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Are there any unit tests for asynchronous code?
Writing unit tests for asynchronous code brings a few unique challenges. Furthermore, the current state of async support in unit test and mocking frameworks varies and is still evolving. This article will consider MSTest, NUnit and xUnit, but the general principles apply to any unit testing framework.
Are there any async void unit test frameworks?
Async void unit test methods don’t provide an easy way for their unit test framework to retrieve the results of the test. In spite of this difficulty, some unit test frameworks do support async void unit tests by providing their own SynchronizationContext in which its unit tests are executed.
Are there any async Task Unit tests in Visual Studio?
Async unit tests that return Task enjoy wide support from almost all unit test frameworks. MSTest added support in Visual Studio 2012, NUnit in versions 2.6.2 and 2.9.6, and xUnit in version 1.9. So, as long as your unit testing framework is less than 3 years old, async task unit tests should just work.
When does a method become an asynchronous method?
It’s only when the async method reaches an await operator that the method may become asynchronous. The await operator takes a single argument, an “awaitable” such as a Task instance.
When does an async method become asynchronous?
An async method begins executing synchronously. It’s only when the async method reaches an await operator that the method may become asynchronous. The await operator takes a single argument, an “awaitable” such as a Task instance.
Is there a synchronizationcontext for Async void tests?
NUnit provides a SynchronizationContext only for async void unit tests. As of this writing, xUnit is planning to add support for async void unit tests with version 2.0.0.
What happens when an asynchronous method throws an exception?
If the method throws an exception (and doesn’t catch it), then the task is completed with that exception. There are two immediate lessons to draw from this brief overview. First, when testing the results of an asynchronous method, the important bit is the Task it returns.