Improve current API by adding more tests

[TG1999]

In PR #4 basic API has been build, but it need more tests. So this issue can be solved by adding more tests for it and making the API more full proof.

[steven-esser]

@TG1999 So the goal here is for fetchcode to be able to any type of URL you can throw at it.

So for a quick list, here are some it should support:

1. http://
2. https://
3. git://
4. svn://
5. ftp://
6. stfp://

There are probably more that I am missing, but these are a good start. @pombredanne might also have more for you.

As for finding valid URL examples of each of these schemes, that is up to you. It should be easy enough to find a number of these in the wild that you can use for test cases.

[TG1999]

@MaJuRG okay, I am getting you. So we can cover all the VCS based URLs later on, when I will be working on reusing pip's VCS (git, hg, svn, bzr) module. For now I will try to cover all non VCS based URLs. Sounds good ? :D

[steven-esser]

@TG1999 Yes. I would also look at the python3 standard library to see if there is applicable functions/features we can use for some of these non-vcs urls.

[TG1999]

Cool 🙌 @MaJuRG