Unit test

[Hdebbech]

These test cases will cover 92 % of the code base.

it helped detect some Bugs, I will open the found issues:

1. the title of the number annotation is ignored and not found in the json schema
2. the "readOnly" attribute is sometimes written "readonly" and other times "readOnly", maybe we need to define constants.

[SaifJerbi]

Good job @Hdebbech, you are doing 🎨
We have a build problem. It"s a compilation error, please try to fix this issue before i merge your code,

[Hdebbech]

All test cases are failing, they were running fine in my local repo, I am closing this pull request, i will update with the latest changes and check them again.