How to resolve file path with NUnit

Question

I have an ApiController where I work with a file stored in some solution folder:

using var reader = new DatabaseReader(Path.Combine(_environment.ContentRootPath, "Data/GeoLite2-City.mmdb"));

Then I have a unit test where I test that method.
I use Mock to mock the IWebHostEnvironment, but when I run the test I always get that _environment.ContentRootPath is always null.

How can I solve this? Thanks!

Answer 1

Hi @Anonymous thanks for the reply, I am gonna share some more code.

LookupController

[ApiController]
[Route("api/[controller]")]
public class LookupController : ControllerBase
{
    private readonly ILogger<LookupController> _logger;
    private readonly IWebHostEnvironment _hostEnvironment;

    public LookupController(ILogger<LookupController> logger, IWebHostEnvironment hostEnvironment)
    {
        _logger = logger;
        _hostEnvironment = hostEnvironment;
    }

    [HttpPost("city-info")]
    public ActionResult<IEnumerable<CityInfoResource>> LookupCityInfo([FromBody] IEnumerable<string> ips)
    {
            //...

            using var reader = new DatabaseReader(Path.Combine(_hostEnvironment.ContentRootPath, "Data/my-file.mmdb"));

            //...
    }
}

LookupControllerTests

    [TestFixture]
    public class LookupControllerTests
    {
        private readonly Mock<ILogger<LookupController>> _logger;
        private readonly Mock<IWebHostEnvironment> _hostEnvironment;

        public LookupControllerTests()
        {
            _logger = new Mock<ILogger<LookupController>>();
            _hostEnvironment = new Mock<IWebHostEnvironment>();
        }

        [Test]
        public void Test_CityLookup_With_Valid_IPs()
        {
			//...
            var controller = new LookupController(_logger.Object, _hostEnvironment.Object);
            var response = controller.LookupCityInfo(ips);
			//...
        }
    }

The problem is with Path.Combine(_hostEnvironment.ContentRootPath, "Data/my-file.mmdb")

When I run the app, the ContentRootPath is "R:\\Demos\\1\\ip-lookup-app" and the file is found.

When I run the tests, the ContentRootPath is always null.

I already found that thread yesterday, but I could not solve it, I always got it null.

So for now I just copied the same file and folder under the Tests project and changed the controller to using var reader = new DatabaseReader("./Data/GeoLite2-City.mmdb"); so basically the path is relative to either project, but of course it's a bad solution.

Answer 2

you never defined the value to use for ContentRootPath in the Mocked IWebHostEnvironment. if you do not define the Mocked values, they will be null. See docs for your mocking library to initial values