chore(api_core): move universe and endpoint routing logic to gapic_v1 public helpers

[hebaalazzeh]

Centralizes generic routing, mTLS, and universe domain resolution helpers under google.api_core.gapic_v1.client_utils.

Exposes get_api_endpoint, get_default_mtls_endpoint, and get_universe_domain as public API helpers to be used by newly generated clients.

The unit tests added in test_client_utils.py are identical to the generator's original routing test cases in test_service.py.j2 (namely test__get_api_endpoint and test__get_universe_domain), modified only to call the public helpers directly:

• test__get_api_endpoint maps to the new get_api_endpoint helper.
• test__get_universe_domain maps to the new get_universe_domain helper.

[gemini-code-assist]

Code Review

This pull request introduces a new routing module to handle mTLS endpoint resolution and universe domain configuration, along with corresponding unit tests and a test fixture for mTLS environment isolation. It also includes minor refactoring in noxfile.py and test_bidi.py. The reviewer identified an issue with the regex-based endpoint conversion logic in routing.py and suggested a more robust string-based implementation to prevent potential security vulnerabilities.

[hebaalazzeh]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces a new routing module in gapic_v1 to handle API endpoint and universe domain resolution, along with comprehensive unit tests. The feedback suggests improving get_default_mtls_endpoint by making domain suffix checks case-insensitive to correctly handle mixed-case or uppercase endpoints, and adding corresponding test cases to verify this behavior.

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packages/google-api-core/google/api_core/gapic_v1/routing.py (36-47)

Domain names are case-insensitive. Performing case-sensitive checks like .endswith(".googleapis.com") can fail to recognize mixed-case or uppercase endpoints (e.g., foo.GoogleAPIs.com), resulting in a failure to resolve the correct mTLS endpoint. We should convert the endpoint to lowercase before performing suffix checks.

    if not api_endpoint or ".mtls." in api_endpoint.lower():
        return api_endpoint

    lowered_endpoint = api_endpoint.lower()
    if lowered_endpoint.endswith(".sandbox.googleapis.com"):
        # len(".sandbox.googleapis.com") == 23
        return api_endpoint[:-23] + ".mtls.sandbox.googleapis.com"

    if lowered_endpoint.endswith(".googleapis.com"):
        # len(".googleapis.com") == 15
        return api_endpoint[:-15] + ".mtls.googleapis.com"

    return api_endpoint

packages/google-api-core/tests/unit/gapic/test_routing.py (35-52)

Add test cases to verify that get_default_mtls_endpoint correctly handles case-insensitive domain suffixes (e.g., foo.GoogleAPIs.com).

def test_get_default_mtls_endpoint():
    # Test valid API endpoints
    assert get_default_mtls_endpoint("foo.googleapis.com") == "foo.mtls.googleapis.com"
    assert (
        get_default_mtls_endpoint("foo.sandbox.googleapis.com")
        == "foo.mtls.sandbox.googleapis.com"
    )
    # Test case-insensitivity
    assert (
        get_default_mtls_endpoint("foo.GoogleAPIs.com")
        == "foo.mtls.googleapis.com"
    )
    assert (
        get_default_mtls_endpoint("foo.Sandbox.GoogleAPIs.com")
        == "foo.mtls.sandbox.googleapis.com"
    )

    # Test endpoints that shouldn't be converted
    assert (
        get_default_mtls_endpoint("foo.mtls.googleapis.com")
        == "foo.mtls.googleapis.com"
    )
    assert get_default_mtls_endpoint("foo.com") == "foo.com"

    # Test empty/None endpoints
    assert get_default_mtls_endpoint("") == ""
    assert get_default_mtls_endpoint(None) is None