how to test asynchronous methods using nunit

Question

How to test asynchronous methods using nunit?

Answer 1

If you have .NET’s version 5 of the C# compiler then you can use new async and await keywords. attach the link : http://simoneb.github.io/blog/2013/01/19/async-support-in-nunit/

If you can using closure with anonymous lambda function, using thread synchronization.

eg)

[TestFixture]
class SomeTests
{
    [Test]
    public void AsyncTest()
    {
        var autoEvent = new AutoResetEvent(false); // initialize to false

        var Some = new Some();
        Some.AsyncFunction(e =>
        {
            Assert.True(e.Result);
            autoEvent.Set(); // event set
        });
        autoEvent.WaitOne(); // wait until event set
    }

}

Answer 2

You could use NUnits Delayed Constraint

[TestFixture]
class SomeTests
{
    [Test]
    public void AsyncTest()
    {
        var result = false;
        var Some = new Some();
        Some.AsyncFunction(e =>
        {
            result = e.Result;
        });

        Assert.That(() => result, Is.True.After(1).Minutes.PollEvery(500).MilliSeconds);
    }

}

This example is for NUnit 3.6 but earlier versions also support Delayed Constraint, but lookup it up as the syntax is different.