public void TestFindByName()
            {
                //Arrange
                string findName = "fido";
                int    findWeight = 20;
                Dog    foundByName, foundByWeight;

                MammalRepoSimple repo = new MammalRepoSimple();

                repo.Add(new Dog()
                {
                    Name = findName, Weight = 10
                });
                repo.Add(new Dog()
                {
                    Name = "milo", Weight = findWeight
                });
                //act
                foundByName   = repo.GetMammalByName(findName) as Dog;
                foundByWeight = repo.GetMammalByWeight(findWeight) as Dog;

                //assert
                Assert.AreEqual(findName, foundByName.Name);
                Assert.AreEqual(findWeight, foundByWeight.Weight);
            }
            public void TestFindByWeightReturnsNullIfNotFound()
            {
                //Arrange

                int findWeight = 22;
                Dog foundByWeight;

                MammalRepoSimple repo = new MammalRepoSimple();

                repo.Add(new Dog()
                {
                    Name = "fido", Weight = 10
                });
                repo.Add(new Dog()
                {
                    Name = "milo", Weight = 20
                });
                //act
                foundByWeight = repo.GetMammalByWeight(findWeight) as Dog;


                //assert
                Assert.IsNull(foundByWeight);
            }