test(geocoding): hard regression tests for enable_address_descriptor (fixes #540)

[Rahulcse79]

Summary

Fixes #540 — reverse_geocode() got an unexpected keyword argument 'enable_address_descriptor'.

The enable_address_descriptor keyword argument was added to googlemaps/geocoding.py in #516 but is not present in the published 4.10.0 release on PyPI, so end users calling:

gmaps.reverse_geocode((center_lat, center_lon), enable_address_descriptor=True)

still hit a TypeError. This PR locks the public surface down with a hard, regression-proof test suite so the kwarg can never silently disappear from a future release again.

What changed

• New file: tests/test_geocoding_advanced.py — 17 tests + 9 sub-tests, all passing.

The new tests cover:

• inspect.signature guards on both geocoding.reverse_geocode and Client.reverse_geocode (signature-level regression for Release failed - unexpected keyword argument: enable_address_descriptor still not supported #540).
• Exact reproduction of the failing call from the bug report — asserts no TypeError is raised.
• enable_address_descriptor=True → sends enable_address_descriptor=true on the wire.
• Default / False / falsy values (None, 0, "", [], {}) omit the parameter.
• Truthy non-bool values (1, "yes", ["x"], {"a":1}) send "true".
• Combined with result_type, location_type, language.
• Works with all latlng input forms: tuple, list, dict, "lat,lng" string, and place_id string.
• address_descriptor (landmarks + areas) is parsed correctly from the response.
• Repeated calls don't leak the parameter across requests.
• Module-level call (geocoding.reverse_geocode(client, ...)) also works.
• Negative test: an unknown / typo'd kwarg still raises TypeError.

Test results

tests/test_geocoding.py ................. [ 17 passed ]
tests/test_geocoding_advanced.py ......... [ 17 passed, 9 sub-tests ]
Full suite: 122 passed

Note for maintainers

A new release (e.g. 4.10.1) cut from master would close #540 for end users on PyPI. These tests guarantee any future refactor of reverse_geocode keeps the documented kwarg.