InternalsVisibleTo usage
I do not know if you know InternalsVisibleToAttribute
I have used on a project https://github.com/ignatandrei/WorldBankAPi , that deals with World Bank API to get information
Let’s take an example: Countries: http://api.worldbank.org/countries?format=json
I have had a class CountriesRepository, that deals with transforming countries Json from WorldBank to Country classes. How can I test it WITHOUT relying on reading data from the internet ?
Simple:
1. Make an interface to grab JSON , IJSonData
1 2 3 4 | public interface IJsonData{ Task<string> JsonData(int page = 1);} |
2. Make a class JSONCountry that reads JSON from HTTP and implements IJSonData
3. Make the CountryRepository class with 2 constructors – one with IJSonData and the default calling JSONCountry
01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 | [assembly: InternalsVisibleTo("WorldBank.Test")]namespace WorldBank.Repository{ public class CountriesRepository { private IJsonData data; public CountriesRepository():this(new JsonCountries()) { }//this is internal - could not see by outside projects with exception of WorldBank.Test//see InternalsVisibleTo above internal CountriesRepository(IJsonData data) { this.data = data; } }} |
Optional: when testing manually, save the json into same files on the hard disk – you will need for point 5
4. The code that will use CountryRepository in official way will use the default – will not see the one with IJSonData
1 2 | var c = new CountriesRepository();var data = c.GetCountries().Result; |
5. The testing code will define another class JSONFromHard that implements IJSonData and reads data from Hard
1 2 3 4 5 6 | class JsonFromHard : IJsonData{//code to read files from disk // you have saved those when testing manually //see point 2 the optional part } |
6. Because I have defined InternalsVisibleToAttribute to the WorldBank.Test, the Test dll can see the constructor with IJSonData and then it class with JSONFromHard – and I have no dependecy on the Http
1 2 3 4 5 6 7 | public void GetAndInterpretData() { //uses [assembly: InternalsVisibleTo("WorldBank.Test")] var c = new CountriesRepository(new JsonFromHard("Countries")); var data = c.GetCountries().Result; Assert.Equal(218, data.Length); } |
You can download the project from https://github.com/ignatandrei/WorldBankAPi to see working.