fix: restore shadowed test_discovery_http_is_closed test

[skippdot]

Fixes #2757

tests/test_discovery.py has contained two class Discovery(unittest.TestCase) definitions since September 2020 (#1038). The second definition silently shadows the first, so its only test, test_discovery_http_is_closed, has never been collected — pytest picks up 0 instances of it on main. The dead test also could not have passed if it ever ran: it calls assert_called_once() on HttpMock.close, a plain method, which raises AttributeError.

Changes

• Remove the shadowed duplicate class.
• Re-add test_discovery_http_is_closed inside the surviving Discovery class, rewritten to patch httplib2.Http so the assertion targets a real mock. It verifies that build() closes the temporary http client it creates to fetch the discovery document (discovery.py, the discovery_http.close() call).
• Pass cache_discovery=False in addition to static_discovery=False, so the discovery document is always fetched through the mocked client — a discovery-cache hit cannot bypass the code path under test.

One file, +14/−7.

Verification

• Collected tests in tests/test_discovery.py: 173 → 174.
• Mutation check: with the discovery_http.close() call removed from googleapiclient/discovery.py, the restored test fails; with it in place, the test passes — so it genuinely guards the close behavior.
• Full tests/ folder on Python 3.14: 339 passed, 1 skipped.
• black --check clean; flake8 --select=E9,F63,F7,F82 (the set CI enforces) clean.

Note: running tests/test_discovery.py in isolation shows one pre-existing failure, DiscoveryErrors::test_tests_should_be_run_with_strict_positional_enforcement — that is #2755, reproducible on an unmodified main, and untouched by this PR.

[gemini-code-assist]

Code Review

This pull request refactors the test_discovery_http_is_closed test in tests/test_discovery.py. The test was moved to the Discovery test class and updated to use @mock.patch on httplib2.Http to verify that the temporary HTTP client created during service discovery is properly closed, preventing connection leaks. There are no review comments, so I have no feedback to provide.

[skippdot]

Noting for reviewers: #2758, opened earlier, addresses the same issue (#2757) with a similar approach (remove the shadowed class, re-add the test with httplib2.Http patched). Differences in this PR:

• passes cache_discovery=False in addition to static_discovery=False, so a discovery-cache hit cannot bypass the mocked client and make the test fail spuriously;
• patches via http_class.return_value instead of a two-mock side_effect, so the test does not depend on build() constructing exactly two Http instances in a particular order;
• mutation-checked: with the discovery_http.close() call removed from discovery.py, the test fails.

#2758 additionally asserts that the caller-facing http client is not closed, which is a nice extra check. Happy to fold that assertion in here, or to defer to #2758 if maintainers prefer it — flagging the overlap so both are not reviewed in parallel unknowingly.