add global testset

[gpucce]

PR Checklist

If you are contributing to Javis.jl, please make sure you are able to check off each item on this list:

• Did I update CHANGELOG.md with whatever changes/features I added with this PR?
• Did I make sure to only change the part of the file where I introduced a new change/feature?
• Did I cover all corner cases to be close to 100% test coverage (if applicable)?
• Did I properly add Javis dependencies to the Project.toml + set an upper bound of the dependency (if applicable)?
• Did I properly add test dependencies to the test directory (if applicable)?
• Did I check relevant tutorials that may be affected by changes in this PR?
• Did I clearly articulate why this PR was made the way it was and how it was made?

Link to relevant issue(s)
Closes #440

How did you address these issues with this PR? What methods did you use?

[gpucce]

@Wikunia about what you asked on #441, try to check the output of the tests to see if you like it, the fact is that if all tests go well it does not show you much, whereas if they don't then it does.

[codecov-commenter]

Codecov Report

Merging #441 (1f9a7ed) into master (8273872) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #441   +/-   ##
=======================================
  Coverage   96.19%   96.19%           
=======================================
  Files          36       36           
  Lines        1603     1603           
=======================================
  Hits         1542     1542           
  Misses         61       61           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8273872...1f9a7ed. Read the comment docs.

[Wikunia]

I assume it shouldn't be in draft state, right? Will merge if you're done with it.