using System;

using System.Collections.Generic;

using System.Linq;

​

public class Program

{

    public static void Main()

    {

        new UnitTests().PerformUnitTest();

    }

}

​

// INSTRUCTIONS:

// The CustomerManager class will be used inside a .NET web aplication.  It has 

// an UpdateZip() method that updates a customer's zip code after validating it.  

// That method needs to make an API call to get valid zip codes, retrieve a value

// from the current HttpContext, and access a repository class.  

//

// All of those external calls makes unit testing difficult. (It currently doesn't

// even complile because of those dependencies.)  Refactor CustomerManager 

// so that PerformUnitTest() can execute without directly invoking any of these

// other services.  After running, two PASS lines should appear in the console.  

// (If necessary, update other classes so that tests can execute.)

//

// Leave UpdateZip() in a state where someone can later make it interact with the 

// HttpContext and DbContext when run in the context of the real application.

//

​

public class UnitTests

{

    public void PerformUnitTest()

    {

        List<string> testZipCodes = new List<string>{"12345", "39205", "22122"};

        var sut = new CustomerManager(testZipCodes);

        // No need to make any changes to this method below this line.

        var expected = true;

        var actual = sut.UpdateZip("12345"); // GOOD zip code

        var result = expected == actual ? "PASS" : "FAIL";

        Console.WriteLine(result);

        expected = false;

        actual = sut.UpdateZip("9999"); // BAD zip code

        result = expected == actual ? "PASS" : "FAIL";

        Console.WriteLine(result);

    }

}

​

public class CustomerManager

{

    public Microsoft.AspNetCore.Http.HttpContext httpContext;

    public List<string> allZipCodes;

    public CustomerRepository repository;

    public CustomerManager(Microsoft.AspNetCore.Http.HttpContext context) //Constructor for normal use

    {

        httpContext = context;

        allZipCodes = GetAllValidZipCodes();

        repository = new CustomerRepository();

    }

    public CustomerManager(List<string> testZipCodes) //Constructor for testing

    {

        httpContext = null;

        allZipCodes = testZipCodes;

        repository = new TestCustomerRepository();

    }

    public bool UpdateZip(string newZipCode)

    {

        if (allZipCodes.Contains(newZipCode))

        {

            // The real application will need access to the current HttpContext

            int? customerId = (int?)httpContext?.Items["CustomerId"] ?? 0;

            repository.UpdateZip(customerId.Value, newZipCode);

            return true;

        }

        else

        {

            return false;

        }

    }

​

    private List<string> GetAllValidZipCodes()

    {

        var httpClient = new HttpClient();

        return httpClient.Get<List<string>>("http://somezipcodeapi.com/GetAll");

    }

}

​

public class Customer

{

    public int ID { get; set; }

​

    public string ZipCode { get; set; }

}

​

public class CustomerRepository

{

    public virtual void UpdateZip(int customerId, string newZipCode)

    {

        var db = new DbContext();

        var customer = db.Customers.SingleOrDefault(i => i.ID == customerId);

        customer.ZipCode = newZipCode;

    }

}

​

public class TestCustomerRepository : CustomerRepository //Overriding with derived class for testing

{

    public override void UpdateZip(int customerId, string newZipCode) {}

}

​

public class DbContext

{

    public List<Customer> Customers { get; set; }

}

​

public class HttpClient

{

    public T Get<T>(string url)

    {

        // perform HTTP call and return response

        return default(T);

    }

}