test: close OPA adapter review coverage gaps

[dinakarjs]

Follow up the nonblocking review on #73 with three test cases: reject invalid elements inside the ids list, preserve successful challenge/error mapper outputs, and map an omitted result to not_applicable. The unhashable-mapper correction and its dict/list controls are already on main; this PR preserves them. Production source, schema and contract are unchanged.

Validation on Python 3.12: full unittest suite 151 tests, 2 skipped. The runner inherited OTEL_TRACES_SAMPLER=parentbased_traceidratio with OTEL_TRACES_SAMPLER_ARG=0.01; clearing OTEL_TRACES_SAMPLER for the test process restored the default recording behavior. No tracing environment is modified persistently. The first run with inherited sampling failed three unrelated span-recording checks; these are not claimed as fixed by this PR.

Three isolated mutations were detected: removing ids element validation (4 failures), mapping challenge/error to deny (2 failures), and defaulting missing result to False (1 failure). Source restored and git diff --check passes. These controls verify adapter behavior only, not policy enforcement or OPA service execution.

[github-actions]

🟡 Contributor Check: MEDIUM

Check	Result
Profile	MEDIUM
Credential	LOW
Overall	MEDIUM

Automated check by AgenTrust Contributor Check.

[rajnisht7]

The changes looks good, this PR adds three focused tests that close the remaining OPA coverage gaps from the earlier review, which are invalid ids elements, challenge/error mapper paths, and omitted result -> not_applicable.

[dinakarjs]

Refreshed current main at e193283; the merge brings in the current dependency locks and does not change this PR's tests or runtime source. Installed the resulting hash-pinned test lock, then validated on Python 3.12: 151 unittest cases run, 149 passed and 2 skipped. Version, bundled-schema, OTel compatibility, TypeScript-schema parity and conformance-fixture checks pass; diff whitespace checks pass. Published tree matches the tested tree. Hosted checks and fresh independent review remain separate.

[dinakarjs]

@imran-siddique current head e193283 is approved by @rajnisht7, who is listed in this repository's maintainer policy, and all seven hosted checks pass. The branch is current and mergeable. I attempted a normal head-pinned squash merge under the user's instruction to close the work, but the GitHub connector returned 403 Resource not accessible by integration. Please merge through the normal maintainer path; no branch rule or approval bypass is requested.