A helper to build dependencies for unit tests that still allow you to substitute your own behaviors in.

ServiceBuilder.cs

public class LocationServiceBuilder
{
    //create default behaviors
    IHttpService _httpService = Mock.Create<IHttpService>();
    IFileService _fileService = Mock.CreateLike<IFileService>(fs => fs.ReadAllLines(Arg.AnyString) == new string[] { "key" });

    //pass in your own dependency if needed
    public LocationServiceBuilder WithHttpService(IHttpService httpService)
    {
        _httpService = httpService;
        return this;
    }
    
    //pass in your own dependency if needed
    public LocationServiceBuilder WithFileService(IFileService fileService)
    {
        _fileService = fileService;
        return this;
    }
   
    //Build the service
    public LocationService Build()
    {
        return new LocationService(_httpService, _fileService);
    }
    
    //setup other test data as needed
    public string GetPlaceDetailsTestResults(string placeId)
    {
        return "example string..";
    }
}

[TestMethod]
public void GetPlaceDetails_WithAPlaceId_ReturnsTheGooglePlace()
{
    //Arrange
    var serviceBuilder = new LocationServiceBuilder();
    var placeId = "10302";
    var httpService = Mock.Create<IHttpService>();
    Mock.Arrange(() => httpService.GetResponse(Arg.AnyString))
        .Returns(serviceBuilder.GetPlaceDetailsTestResults(placeId));
    var service = serviceBuilder.WithHttpService(httpService).Build();

    //Act
    var result = service.GetPlaceDetails(placeId).result;

    //Assert
    Assert.AreEqual(placeId, result.place_id);
}