public void Eager_Validation_Source_WithValueTask()
 {
     Assert.Throws <ArgumentNullException>(() =>
     {
         var iter = AsyncEnumerable.Append <int>(null, new ValueTask <int>(0));
     });
 }
 public void Eager_Validation_Source()
 {
     Assert.Throws <ArgumentNullException>(() =>
     {
         var iter = AsyncEnumerable.Append <int>(null, 0);
     });
 }
        public void Eager_Validation_Task()
        {
            var target = new ThrowingAsyncEnumerable <int>();

            Assert.Throws <ArgumentNullException>(() =>
            {
                var iter = AsyncEnumerable.Append(target, (Task <int>)null);
            });
        }