Deleted and Inserted indexes not being tested

[AleLudovici]

Hi,

I've noticed that the unit tests are not asserting correctly that insertion and deletions happens at the expected indexes. Expectations were only being fulfilled but not asserted.
I've also took the chance to refactor the Unit test to improve the readability and to separate them by test domain.
I've already open a PR #51 with the proposed changes.

Thanks

[AleLudovici]

Hi @jflinter any chance you could have a look at this issue?
I've opened a PR #51 with the changes.

Let me know,
thanks