标签：NUnit non Task return void test async
Error `Async test method must have non-void return type` when upgrading from NUnit 2 to NUnit 3
回答
The error
Async test method must have non-void return type
means that in NUnit 3+, an async Unit Test itself may not have a void return type (i.e. the method decorated with [Test] / [TestCase] etc). Instead, you can return an empty Task (Correct way in newer versions of NUnit with async test support):
[Test]
public async Task EnsureFoo()
{
// Arrange
// Act
var myResult = await classBeingTested.DoSomethingAsync();
// Assert
Assert.IsNotNull(myResult);
...
}
In NUnit 2.x, this wasn't checked, so a async void unit test could slip into your unit test code base, i.e. of the form (Bad, don't do this)
[Test]
public async void Foo() // < -- Error : Async test method must have non-void return type
{
var myResult = await classBeingTested.DoSomethingAsync();
// Post continuation assertions here.
}
this is rather dangerous - the test can't be awaited*, and would return before any continuations completed - e.g. any failures in the Asserts done in the continuation might not be reported.
Re : Your fake Task
Scheduling a Task just to return a fake response seems overkill, i.e. in most tests you should be able to use Task.FromResult to replace:
Func<Task<HttpResponseMessage>> continuation =
() => Task.Factory.StartNew(() => expectedResponseMessage);
With the cheaper:
Func<Task<HttpResponseMessage>> continuation =
() => Task.FromResult(expectedResponseMessage);
Task.FromResult returns an already completed task with the given return value - in most cases, this should suffice for your unit testing purposes, unless you really do want an independent Task to be executed on the threadpool.
* Actually, seemingly even earlier versions such as NUnit 2.6.4 had already identified the issue with async void tests, and incorporated a workaround
标签：NUnit,non,Task,return,void,test,async 来源： https://www.cnblogs.com/chucklu/p/16441249.html
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