Add DatasetDao tests

[wslulciuc]

Our test coverage for DatasetDao is currently < 25%, let's add some tests to get it closer to 75%

codecov link: https://codecov.io/gh/MarquezProject/marquez/src/master/src/main/java/marquez/db/DatasetDao.java

[hjpatel16]

Hey, I would like to work on it

[wslulciuc]

Hey @hjpatel16. Great to hear you'd like to help out! I'm actually fixing this issue in PR #395 (sorry, should've assigned this to myself sooner). Once merged into master, it will serve as an example on how to write tests for our DAO classes.

Is there an issue tagged with "good first issue" you'd like to pick up?

[hjpatel16]

Actually, I was looking more than "good first issue" where I would be able to code more and contribute more. Let me know if you know any specific issue which will be perfect for me

[wslulciuc]

@hjpatel16, sure! How does adding a factory method to our response models sound? Full details can be found here #309. I know the issues related to the epic are labeled as "good first issue", but these changes are non-trivial and would require writing tests, with new methods used right away in our resource classes.

Let me know if that's something you're interested in.

NOTE: You would need a separate PR per issue in the epic

[hjpatel16]

Yes, I would like to work on that epic. Thanks @wslulciuc, much appreciated

[wslulciuc]

Fixed #395