[jr-rk]

Purpose

Testing infrastructure only. Adds CI + characterization tests tailor-made for
main's usage surface — how the three main-lineage consumers
(dspace-import-clarin, dspace-rest-test, dspace-item-importer) actually
call this library. No dspace_rest_client/ changes. Targets dtq and
proposes nothing for main.

Shared-surface fixes the tests would otherwise pin are split into a stacked PR
(fix/clarin-shared-surface-hardening) so this one stays scoped to test/CI.

What's here

• CLARIN counterpart to test_repo_usage_contract.py: per-method and
  whole-chain characterization tests, only the HTTP transport mocked (the real
  client builds URLs and parses responses).
• _helpers.py CLARIN builders, pytest.ini markers, requirements-test.txt.
• .github/workflows/tests.yml: branch-aware triggers plus a
  differential-contract job that runs the shared CLARIN contract against
  both the dtq and the main implementation. The main leg checks
  origin/main's client into the CI runner to test against it — read-only,
  nothing is written back to main. A contract green on both is what a future
  merge would need to preserve.

Markers

• clarin — shared contract, must hold on both main and dtq.
• dtq_only — existing dtq-only surface/behaviour, deselected on the main leg.

Verified locally

• Leg A (full suite, dtq impl): 123 pass.
• Leg B (shared contract, main impl): 44 pass, 3 dtq_only deselected.

[vidiecan]

Rebased onto dtq a62a63e + review fixes

New head: 13ba16c (rebased commit 13d0243 + one review commit). Note: #22 shares this head branch, so it moved too.

Conflict resolution

• tests/_helpers.py - kept both sides: dtq's no_warnings_logged (3.8-safe assertNoLogs stand-in, fix(models): parse resource policies granted to an eperson #27) and load_fixture, plus this PR's CLARIN builders (raw_policy_json, group_json, user_json, label_json, license_json, clarin_allowance_json, search_envelope). No other conflicts; dtq's fix(models): parse resource policies granted to an eperson #27/fix(client): log expected 401/404 fetch failures as concise warnings #28/fix(client): follow pagination and verify counts in list getters #29/fix(client): Python correctness sweep - logging, timeouts, file handle, None guards #20 changes are untouched (this PR still changes no dspace_rest_client/ code).

Review fixes (tests/CI only)

Finding	Change	Test
test_invalid_dso_returns_self_without_request pinned a bug (remove_metadata(None, ...) returning the client); #25 changes it to None, so whichever landed second would go red	Renamed to test_invalid_dso_sends_no_request_and_returns_no_dso: asserts no request is sent and the result is not a DSpaceObject - holds for both self and None	passes on dtq and main legs
add_member body was never asserted	New shared (clarin, not dtq_only) test_posts_eperson_uri_list_and_returns_true_on_204: text/uri-list, exactly one absolute URI under the API ending in /epersons/{uuid}. DSpace resolves only the trailing UUID, so both /epersons/{uuid} (main/dtq today) and the canonical /eperson/epersons/{uuid} (#24) satisfy it	passes on dtq and main legs
consumer-smoke checked out private consumer repos with CONSUMER_READ_TOKEN and default persist-credentials, then ran PR code	persist-credentials: false on that checkout	workflow change

Verified locally

• Full suite + --cov-fail-under=70: 143 passed, 72% coverage.
• Differential contract: dtq leg 48 passed; main leg 45 passed, 3 dtq_only deselected.
• Python 3.8.20: 143 passed.

Deferred (not changed here)

• Chain tests in test_clarin_usage_contract.py are not truly chained (some feed hand-built objects instead of the previous call's result, eg. create_submit_group(type("C", (), {...})())).
• Some per-method tests duplicate the chain tests (eg. the bundle-by-name lookups).