public void GetCountryExtension_ReturnsPhoneNumberExtension()
        {
            //Arrange
            var countries = new List <CountryIdentifiers>
            {
                new CountryIdentifiers()
                {
                    CountryId      = 1,
                    CountryCode    = "NZ",
                    PhoneExtension = "64"
                },
                new CountryIdentifiers()
                {
                    CountryId      = 2,
                    CountryCode    = "AU",
                    PhoneExtension = "61"
                }
            }.AsQueryable();

            string countryCode    = "NZ";
            string phoneExtension = "64";
            var    mockSet        = new Mock <DbSet <CountryIdentifiers> >();

            mockSet.As <IQueryable <CountryIdentifiers> >().Setup(m => m.Provider).Returns(countries.Provider);
            mockSet.As <IQueryable <CountryIdentifiers> >().Setup(m => m.Expression).Returns(countries.Expression);
            mockSet.As <IQueryable <CountryIdentifiers> >().Setup(m => m.ElementType).Returns(countries.ElementType);
            mockSet.As <IQueryable <CountryIdentifiers> >().Setup(m => m.GetEnumerator()).Returns(countries.GetEnumerator());

            var mockContext = new Mock <StudentContext>();

            mockContext.Setup(c => c.CountryIdentifiers).Returns(mockSet.Object);

            //Act
            var repo    = new CountryIdentifiersRepository(mockContext.Object);
            var results = repo.GetCountryExtension(countryCode);

            //Assert
            Assert.AreEqual("64", results);
        }