Paginator

[anujhydrabadi]

Description

paginator() method in PagedIterable to support starting at a particular page, and next, previous, first, last and jumping to any particular page, along with a few other supporting methods. Made in parallel to iterator() method so as to keep backward compatibility, but supports all functionality that iterator() provides.

Fixes #348
Fixes #1614
Fixes #448
Fixes #1197

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[anujhydrabadi]

Pending tasks:

• Test refresh() method by changing underlying data.
• Make a few hacky if conditions in GitHubPaginator (w.r.t. the next variable) more readable.
• Revise and fix javadocs.
• Capturing snapshot test data.

Question for maintainers/reviewers:

• Should I cover every flow that calls PagedIterable with tests? Will be a huge task to have adequate tests for all of them. Currently I have picked one flow (workflow runs) where I am testing every possible case, and assuming the rest of the flows will comply, given the common nature of the APIs.
• I have tests that make assertions on the values of the underlying data, and would fail once that data changes. Should I avoid such tests and think of more creative ways to make my assertions independent of the underlying data, or is it fine? Or is there any other way?

Review comments on the overall design/implementation/behaviour of the methods are welcome, even though it is a WIP PR for now.

[bitwiseman]

Question for maintainers/reviewers:

• Should I cover every flow that calls PagedIterable with tests? Will be a huge task to have adequate tests for all of them. Currently I have picked one flow (workflow runs) where I am testing every possible case, and assuming the rest of the flows will comply, given the common nature of the APIs.

I would assume that testing one scenario per implementation should generally be sufficient. You'll need to test search scenario separately.

• I have tests that make assertions on the values of the underlying data, and would fail once that data changes. Should I avoid such tests and think of more creative ways to make my assertions independent of the underlying data, or is it fine? Or is there any other way?

Ideally, you should find scenarios where the underlying data doesn't change. However, if that isn't possible, once you record the test data you can mark the test as requiring custom data so that someone doesn't try to re-record it later without knowing the issues. If you go this path, be sure to add comments explaining how to update/re-record test data in future.

[bitwiseman]

If this is going to be present on this class, we'll need to pass startPage to the Iterator as well.

[bitwiseman]

I'm not sure I understand why we need a separate Paginator class. It tries to smash together item iteration with page iteration. I think if people want to navigate by pages we should have a toPages(int pageSize) that returns a GitHubPageIterable or even a GitHubPageIterator (which already exists but is currently internal). Either way, this should handle iterating only over pages not their contents.

Overall I woud expect most of this to do via adding methods to existing classes, PagedIterable, PagedIterator, GitHubPageIterator, GitHubPageContentsIterable and GitHubPageContentsIterable.GitHubPageContentsIterator.

If you feel extremely strongly about this, I would even discuss pushing all the functionality of Paginator into PagedIterable and PagedIterator since it seems to be reimplementing significant portions of those classes.