Move tests to aws-smithy-mocks

[simonmarty]

Issue #, if available:

Description of changes: Accidentally closed #112 on a force push.

Move unit tests to aws-smithy-mocks for easier test coverage.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

❌ Patch coverage is 97.92746% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.72%. Comparing base (01429bb) to head (0401ce1).

Files with missing lines	Patch %	Lines
aws_secretsmanager_caching/src/lib.rs	97.92%	8 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #119      +/-   ##
==========================================
+ Coverage   92.14%   92.72%   +0.57%     
==========================================
  Files          14       14              
  Lines        2405     2734     +329     
  Branches     2405     2734     +329     
==========================================
+ Hits         2216     2535     +319     
- Misses        143      150       +7     
- Partials       46       49       +3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[reyhankoyun]

This evaluates to a bool that's silently discarded. The test passes even if the error message is completely wrong. I think we need to add assert!():

Err(e) => assert!(e.to_string().contains("Access to KMS is not allowed")),    

[reyhankoyun]

Should this be resolved before merging? The old mock returned raw HTTP with "__type":"AccessDeniedException" which the SDK deserializes into the proper error variant. The new mock uses DescribeSecretError::generic(...) which is an unmodeled error. If the code under test distinguishes AccessDeniedException from other errors, this test is weaker than before. If it doesn't, we should remove the TODO.

[simonmarty]

Whoops, completely missed that. Will find a way to address the TODO in the next rev.

[reyhankoyun]

The is_current tests (test_get_cache_is_current_fast_refreshes, test_is_current_version_id_succeeds, test_is_current_version_stage_succeeds, test_is_current_both_version_id_and_version_stage_succeed) share ~90% identical setup: same GSV mock, same describe mock, same client construction, same assertion loop. A helper that takes optional version_id/version_stage and returns a configured client + mock rules would cut a lot of duplication. The old code had fake_client() for this, looks like we removed it for mock-based tests but didn't replace it.