public void GetAllCountries_ReturnsAllRecords()
        {
            //This test is the basic layout if you want to simulate database queries using linq.
            //Arrange
            var countries = new List <CountryIdentifiers>
            {
                new CountryIdentifiers()
                {
                    CountryId      = 1,
                    CountryCode    = "NZ",
                    PhoneExtension = "64"
                },
                new CountryIdentifiers()
                {
                    CountryId      = 2,
                    CountryCode    = "AU",
                    PhoneExtension = "61"
                }
            }.AsQueryable();

            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 service = new CountryIdentifiersRepository(mockContext.Object);
            var results = service.GetAllCountries().ToList();

            //Assert
            Assert.AreEqual(2, results.Count());
            Assert.AreEqual("NZ", results[0].CountryCode);
            Assert.AreEqual("AU", results[1].CountryCode);
        }