test: add unit tests for Paginator class — core pagination logic has no direct coverage

[ausbernard]

Gap

Paginator is a core feature — it's the engine behind every .all() call in the library — but it has zero direct unit
tests. It's only exercised indirectly through integration tests like test_customers_all_pages, which test the full HTTP
stack rather than the pagination logic itself.

Tests Added

tests/paginator_test.py covers the paginator in isolation using unittest.mock (no HTTP mocking needed):

Test	What it proves
test_single_page_yields_all_records	Stops after one fetch when no after cursor
test_multiple_pages_follows_cursor	Follows cursors until None, collects all records
test_after_cursor_passed_to_next_fetch	Cursor value actually makes it into the next request params
test_empty_page_yields_nothing	Graceful handling of empty responses
test_params_passed_to_service	Filter params reach the service
test_identity_params_passed_to_service	Nested resource params (e.g. creditor_id) pass through correctly
test_original_params_not_mutated	The params dict passed in isn't modified during iteration

collected 7 items

tests/paginator_test.py::test_single_page_yields_all_records PASSED
tests/paginator_test.py::test_multiple_pages_follows_cursor PASSED
tests/paginator_test.py::test_after_cursor_passed_to_next_fetch PASSED
tests/paginator_test.py::test_empty_page_yields_nothing PASSED
tests/paginator_test.py::test_params_passed_to_service PASSED
tests/paginator_test.py::test_identity_params_passed_to_service PASSED
tests/paginator_test.py::test_original_params_not_mutated PASSED

7 passed in 0.31s

PR Ready

Branch at ausbernard/gocardless-pro-python → chore/paginator-test. Same collaborator access situation as my
previous issue — happy to contribute if a PR can be opened.

[jamiecobbett]

Hi @ausbernard thanks for the feedback. The branch you refer to doesn't seem to be published on your fork though? I'll look into adding some tests regardless.

[ausbernard]

Hey, I realized the branch on the fork wasn't present at the time but have since published it! If you haven't written it
yet, feel free to use mine — would love to get the contribution!

[jamiecobbett]

No problem - unfortunately we can't really accept direct contributions as this library is generated from templates using a private binary. We'd like to make all of that public, but can't promise anything.

I've made various changes, plus some extras, so thank you for getting in touch 👍