public void FlowData_GetDataAsEnumerable()
        {
            _flowData.Process();
            string          key  = "key";
            TestElementData data = _flowData.GetOrAdd(
                key,
                (p) => new TestElementData(p));

            var result = _flowData.ElementDataAsEnumerable();

            var count = 0;

            foreach (var elementData in result)
            {
                count++;
                Assert.AreSame(data, elementData);
            }
            Assert.AreEqual(1, count);
        }