public void TestRemoveByIdCommandAndIfFindByIdCommandThrowsExceptionIfTheIdDoesNotExists() { extendedDatabase.Add(new Person(123, "Dani")); extendedDatabase.Add(new Person(1234, "Liya")); extendedDatabase.Add(new Person(12345, "Federica")); extendedDatabase.RemoveById(123); Assert.AreEqual(2, extendedDatabase.People.Count); Assert.That(() => extendedDatabase.FindPersonById(123), Throws.InvalidOperationException .With.Message.EqualTo("No people with that id in collection!")); }