UnitTest in ASP.NET with Postgres - asp.net

Question

I write some tests of created system which worked with PostgreSQL. I create in solution new project with type Class Library (.NET Core). Then, i create class, which testing class DocumentRepository. But in constructor of DocumentRepository is used IConfiguration (for connecting with database), and this IConfiguration i can't call in test class. How i can to imitate connecting with database in UnitTest?
Here class, which i want testing
public class DocumentsRepository : IRepository<Documents>
{
private string connectionString;
public DocumentsRepository(IConfiguration configuration, string login, string password)
{
connectionString = configuration.GetValue<string>("DBInfo:ConnectionString");
connectionString = connectionString.Replace("username", login);
connectionString = connectionString.Replace("userpassword", password);
}
internal IDbConnection Connection
{
get
{
return new NpgsqlConnection(connectionString);
}
}
public void Add(Documents item)
{
using (IDbConnection dbConnection = Connection)
{
dbConnection.Open();
dbConnection.Execute("SELECT addrecuserdocuments(#DocumentName,#Contents,#DocumentIntroNumber)", item);
}
}
Here's test, which i try use
using FluentAssertions;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using WebApplication4.Controllers;
using WebApplication4.Entites;
using WebApplication4.ViewModels;
using Xunit;
namespace TestsApp
{
public class UserControllerTest
{
private IConfiguration configuration;
private string connectionString;
[Fact]
public async Task IndexUsers()
{
connectionString = configuration.GetValue<string>("DBInfo:ConnectionString");
var aCon = new AccountController(configuration);
var uCon = new UserController(configuration);
LoginModel model = new LoginModel
{
Login = "postgres",
Password = "111"
};
aCon.Authorization(model);
var result = uCon.Index();
var okResult = result.Should().BeOfType<OkObjectResult>().Subject;
var persons = okResult.Value.Should().BeAssignableTo<IEnumerable<Documents>>().Subject;
persons.Count().Should().Be(7);
}
}
}
Test show my error on
var result = uCon.Index();
And get me NullReferenceException.
How i can resolve this problem?

Answer 1

First and foremost, you're not unit testing, you're integration testing. As soon as you've got something like a database connection in the mix, unit testing is well out the window. If your goal is to write unit tests for your repository class, you should be mocking the data store.
Second, you should not inject IConfiguration, if you need some data from your configuration, such as a connection string, you should bind it to a strongly-typed class, and inject that instead:
services.Configure<MyConnectionStringsClass>(Configuration.GetSection("ConnectionStrings"));
Then, inject IOptionsSnapshot<MyConnectionStringsClass> instead.
Third, you really shouldn't be handling it this way, anyways. If you repository has a dependency on IDbConnection, then you should be injecting that into your repository. In Startup.cs:
services.AddScoped(p => new NpgsqlConnection(Configuration.GetConnectionString("Foo"));
Then, accept NpgsqlConnection in your repo constructor and set it to a private field.
Fourth, if you insist on continuing the way you currently are, you should absolutely not have a custom getter on your Connection property that news up NpgsqlConnection. That means you'll get a new instance every single time you access this property. Instead, you should define it as simple { get; private set; }, and set it in your repo's constructor.
Fifth, you should not be using using with a property defined in either way, as it will be disposed after the first time you do it, making all subsequent queries fail with an ObjectDisposedException. If you're going to new it up in your class, then your class needs to implement IDisposable and you should dispose of your connection in the Dispose method. FWIW, if you inject all dependencies (including your connection) into your class, you don't need to implement IDisposable as there's nothing the class will own that it needs to dispose of - another great reason to use dependency injection all the way down.
Finally, to answer you main question, you should use TestServer. When creating a TestServer you pass it your Startup class as a type param, so you end up with a true replica of your actual app, with all the appropriate services and such. Then, you can issue HTTP requests, like you would with HttpClient to test your controller actions and such. However, again, this is for integration testing only, which is the only time you should actually have a PostreSQL database in-play anyways.