public void Throw_ArgumentException_When_Calling_Retrieve_Questions_With_Non_Positive_Limit_Argument()
        {
            // Arrange
            var controller = new ExamsController(GetFakeContext(), GetUserManagerMock().Object);

            // Act
            var positiveResult = controller.RetrieveQuestions(1, 0);

            // Assert
            Assert.IsAssignableFrom <List <Question> >(positiveResult);
            Assert.Throws <ArgumentException>(() => controller.RetrieveQuestions(0, 0));
            Assert.Throws <ArgumentException>(() => controller.RetrieveQuestions(-1, 0));
        }