// Licensed to the .NET Foundation under one or more agreements. // The .NET Foundation licenses this file to you under the Apache 2.0 License. // See the LICENSE file in the project root for more information. using System; using System.Collections.Generic; using System.Linq; using System.Threading; using System.Threading.Tasks; using Xunit; namespace Tests { public class ElementAtOrDefault : AsyncEnumerableTests { [Fact] public async Task ElementAtOrDefault_Null() { await Assert.ThrowsAsync(() => AsyncEnumerable.ElementAtOrDefault(default, 0)); await Assert.ThrowsAsync(() => AsyncEnumerable.ElementAtOrDefault(Return42, -1)); await Assert.ThrowsAsync(() => AsyncEnumerable.ElementAtOrDefault(default, 0, CancellationToken.None)); await Assert.ThrowsAsync(() => AsyncEnumerable.ElementAtOrDefault(Return42, -1, CancellationToken.None)); } [Fact] public void ElementAtOrDefault1() { var res = AsyncEnumerable.Empty().ElementAtOrDefault(0); Assert.Equal(0, res.Result); } [Fact] public void ElementAtOrDefault2() { var res = Return42.ElementAtOrDefault(0); Assert.Equal(42, res.Result); } [Fact] public void ElementAtOrDefault3() { var res = Return42.ElementAtOrDefault(1); Assert.Equal(0, res.Result); } [Fact] public void ElementAtOrDefault4() { var res = new[] { 1, 42, 3 }.ToAsyncEnumerable().ElementAtOrDefault(1); Assert.Equal(42, res.Result); } [Fact] public void ElementAtOrDefault5() { var res = new[] { 1, 42, 3 }.ToAsyncEnumerable().ElementAtOrDefault(7); Assert.Equal(0, res.Result); } [Fact] public void ElementAtOrDefault6() { var ex = new Exception("Bang!"); var res = Throw(ex).ElementAtOrDefault(15); AssertThrows(() => res.Wait(WaitTimeoutMs), ex_ => ((AggregateException)ex_).Flatten().InnerExceptions.Single() == ex); } } }