How do you mock an IAsyncEnumerable?

Question

I want to unit test a method that calls another method of a service returning an IAsyncEnumerable. I have created a a mock of my service Mock<

Answer 1

I recommend using ToAsyncEnumerable from System.Linq.Async, as Jeroen suggested. It seems like you're using Moq, so this would look like:

async Task MyTest()
{
  var mock = new Mock();
  var mockData = new[] { "first", "second" };
  mock.Setup(x => x.CallSomethingReturningAsyncStream()).Returns(mockData.ToAsyncEnumerable());

  var sut = new SystemUnderTest(mock.Object);
  var result = await sut.MyMethodIWantToTest();

  // TODO: verify `result`
}