使用NSubstitute的单元测试无效方法

Question

I want to test if the Update or Insert function is called with a unit test. What would the unit test look like for this?

public void LogicForUpdatingAndInsertingCountriesFromMPtoClientApp()
{
   var allCountriesAlreadyInsertedIntoClientDatabase = _countryBLL.GetAllCountries();
   var countiresFromMP = GetAllCountriesWithTranslations();
   List<Country> countiresFromMPmapped = new List<Country>();
   foreach (var country in countiresFromMP)
   {
       Country newCountry = new Country();
       newCountry.CountryCode = country.Code;
       newCountry.Name = country.TranslatedText;
       countiresFromMPmapped.Add(newCountry);
   }
   foreach (var country in countiresFromMPmapped)
   {
      //check if the country is already inserted into the Client Database,
      //if it is update, else insert it
       Country testedCountry = allCountriesAlreadyInsertedIntoClientDatabase
                               .Where(x => x.CountryCode == country.CountryCode)
                               .FirstOrDefault();
      //here fallback function for tested country
      if (testedCountry != null)
      {
          var countryToUpdate = _countryBLL.GetCountryByCode(testedCountry.CountryCode);
          //return _countryBLL.UpdateCountry(countryToUpdate);
          _countryBLL.UpdateCountry(countryToUpdate);
      }
      else
      {   
          country.CountryId = Guid.NewGuid();
          // return  _countryBLL.InsertCountryFromMP(country);
          _countryBLL.InsertCountryFromMP(country);
      }

   }
   return null;
}

The method is wrapped in an interface which I can mock.

Answer 1

Are you trying to test for a specific call, or are you happy with just testing either call was received?

For the latter, you can use the ReceivedCalls() extension method to get a list of all the calls a substitute has received:

var allCalls = _countryBLL.ReceivedCalls();
// Assert “allCalls” contains “UpdateCountry” and “InsertCountry”

NSubstitute wasn't really designed to support this, so it is quite messy.

To test a specific call was made, we can use Received() :

_countryBLL.Received().UpdateCountry(Arg.Any<Country>());
// or require a specific country:
_countryBLL.Received().UpdateCountry(Arg.Is<Country>(x => x.CountryCode == expectedCountry));

This requires that the required dependencies have been substituted in for the test, which often results in tests like this:

[Test]
public void TestCountryIsUpdatedWhen….() {
  var countryBLL = Substitute.For<ICountryBLL>();
  // setup specific countries to return:
  countryBLL.GetAllCountries().Returns( someFixedListOfCountries );
  var subject = new MyClassBeingTested(countryBLL);

  subject.LogicForUpdatingAndInsertingCountries…();

  countryBLL.Received().UpdateCountry(…);
}