public void ShouldContainAllInitiallyProvidedElements() { // given var initialList = new List<int>() {1, 2, 3}.ToDictionary(value => value, value => $"#{value}"); // when using (var observableDictionary = new ObservableDictionary<int, string>(initialList)) { // then observableDictionary.IsEmpty.Should().Be(false); observableDictionary.Count.Should().Be(initialList.Count); observableDictionary.ShouldAllBeEquivalentTo(initialList); } }