I'm a bit stuck with this code (this is a sample):
public async Task Fail()
{
await Task.Run(() => { throw new Exception(); });
}
[Test]
public async Task TestFail()
{
Action a = async () => { await Fail(); };
a.ShouldThrow<Exception>();
}
The code doesn't catch the exception, and fails with
Expected a System.Exception to be thrown, but no exception was thrown.
I'm sure I'm missing something, but docs seem to suggest this is the way to go. Some help would be appreciated.
You should use Func<Task> instead of Action:
[Test]
public void TestFail()
{
Func<Task> f = async () => { await Fail(); };
f.ShouldThrow<Exception>();
}
That will call the following extension which is used to verify asynchronous methods
public static ExceptionAssertions<TException> ShouldThrow<TException>(
this Func<Task> asyncAction, string because = "", params object[] becauseArgs)
where TException : Exception
Internally this method will run task returned by Func and wait for it. Something like
try
{
Task.Run(asyncAction).Wait();
}
catch (Exception exception)
{
// get actual exception if it wrapped in AggregateException
}
Note that test itself is synchronous.
With Fluent Assertions v5+ the code will be like :
ISubject sut = BuildSut();
//Act and Assert
Func<Task> sutMethod = async () => { await sut.SutMethod("whatEverArgument"); };
await sutMethod.Should().ThrowAsync<Exception>();
This should work.
Other variation of usage ThrowAsync method:
await Should.ThrowAsync<Exception>(async () => await Fail());