public void WhenAllInstancesOfATypeAreResolvedGenericallyItShouldReturnAllInstances() { // Arrange var expectedItemsList = new List <string> { "All", "Instances", "Are", "Retrieved" }; var container = new ShifterContainer(); container .AddInstance(typeof(int), 1) .AddInstance(typeof(string), "All") .AddInstance(typeof(int), 1) .AddInstance(typeof(string), "Instances") .AddInstance(typeof(int), 1) .AddInstance(typeof(string), "Are") .AddInstance(typeof(int), 1) .AddInstance(typeof(string), "Retrieved"); // Act var resolveAll = container.GetAllInstances <String>(); // Assert resolveAll.Count().Should().Be(4, "because there are 4 instances registered."); resolveAll.Should().Contain(expectedItemsList); }