CLN: cleanup rank tests

[jreback]

we have rank tests in:

Create a new pandas/tests/series/test_rank

• pandas/tests/series/test_analytics

Create a new pandas/tests/frame/test_rank

• pandas/tests/frame/test_analytics

• pandas/tests/test_algos

Let's remove this and split among the other three

• pandas/tests/test_stats

[rouzazari]

@jreback, just so I understand: the end result will have two files (series/test_rank and frame/test_rank), correct?

The rank-related tests from all four source files (series/test_analytics, frame/test_analytics, test_algos, and test_stats) should end up in the relevant test_rank files. All unrelated (i.e. non-rank) tests should remain in the existing files.

[jreback]

yes though you might have some common tests in test_algos (if that makes sense)

[rouzazari]

Great. I submitted a PR. I believe the tests that remain in test_algos should remain there because those tests are not specifically related to Series or DataFrame; they seem to be related to testing rank in general.