test: add unit tests for gapic client_helpers

Author: hebaalazzeh

packages/google-api-core/tests/unit/gapic/test_client_helpers.py

@@ -0,0 +1,133 @@
+# -*- coding: utf-8 -*-
+# Copyright 2026 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import os
+from unittest import mock
+import pytest
+
+from google.api_core.gapic_v1 import client_helpers
+from google.auth.exceptions import MutualTLSChannelError
+
+
+def test__get_default_mtls_endpoint():
+    # Test valid API endpoints
+    assert client_helpers._get_default_mtls_endpoint("foo.googleapis.com") == "foo.mtls.googleapis.com"
+    assert client_helpers._get_default_mtls_endpoint("foo.sandbox.googleapis.com") == "foo.mtls.sandbox.googleapis.com"
+    
+    # Test endpoints that shouldn't be converted
+    assert client_helpers._get_default_mtls_endpoint("foo.mtls.googleapis.com") == "foo.mtls.googleapis.com"
+    assert client_helpers._get_default_mtls_endpoint("foo.com") == "foo.com"
+    
+    # Test empty/None endpoints
+    assert client_helpers._get_default_mtls_endpoint("") == ""
+    assert client_helpers._get_default_mtls_endpoint(None) is None
+
+
+@mock.patch("google.auth.transport.mtls.should_use_client_cert", autospec=True)
+def test__use_client_cert_effective_with_google_auth(mock_should_use_client_cert):
+    # Test when google-auth supports the method
+    mock_should_use_client_cert.return_value = True
+    assert client_helpers._use_client_cert_effective() is True
+    
+    mock_should_use_client_cert.return_value = False
+    assert client_helpers._use_client_cert_effective() is False
+
+
+@mock.patch.dict(os.environ, {}, clear=True)
+def test__use_client_cert_effective_fallback():
+    # We must patch hasattr to simulate google-auth lacking the method
+    with mock.patch("google.api_core.gapic_v1.client_helpers.hasattr", return_value=False):
+        # Default is false
+        assert client_helpers._use_client_cert_effective() is False
+        
+        with mock.patch.dict(os.environ, {"GOOGLE_API_USE_CLIENT_CERTIFICATE": "true"}):
+            assert client_helpers._use_client_cert_effective() is True
+            
+        with mock.patch.dict(os.environ, {"GOOGLE_API_USE_CLIENT_CERTIFICATE": "false"}):
+            assert client_helpers._use_client_cert_effective() is False
+            
+        with mock.patch.dict(os.environ, {"GOOGLE_API_USE_CLIENT_CERTIFICATE": "invalid"}):
+            with pytest.raises(ValueError, match="must be either `true` or `false`"):
+                client_helpers._use_client_cert_effective()
+
+
+def test__get_api_endpoint_override():
+    # If api_override is provided, it should be returned regardless of other args
+    endpoint = client_helpers._get_api_endpoint(
+        api_override="custom.endpoint.com",
+        client_cert_source=None,
+        universe_domain="googleapis.com",
+        use_mtls_endpoint="auto",
+        default_universe="googleapis.com",
+        default_mtls_endpoint="foo.mtls.googleapis.com",
+        default_endpoint_template="foo.{UNIVERSE_DOMAIN}",
+    )
+    assert endpoint == "custom.endpoint.com"
+
+
+def test__get_api_endpoint_mtls_always():
+    # use_mtls_endpoint == "always" should use the default mtls endpoint
+    endpoint = client_helpers._get_api_endpoint(
+        api_override=None,
+        client_cert_source=None,
+        universe_domain="googleapis.com",
+        use_mtls_endpoint="always",
+        default_universe="googleapis.com",
+        default_mtls_endpoint="foo.mtls.googleapis.com",
+        default_endpoint_template="foo.{UNIVERSE_DOMAIN}",
+    )
+    assert endpoint == "foo.mtls.googleapis.com"
+
+
+def test__get_api_endpoint_mtls_auto_with_cert():
+    # "auto" with client_cert_source should use mtls
+    endpoint = client_helpers._get_api_endpoint(
+        api_override=None,
+        client_cert_source=mock.Mock(),
+        universe_domain="googleapis.com",
+        use_mtls_endpoint="auto",
+        default_universe="googleapis.com",
+        default_mtls_endpoint="foo.mtls.googleapis.com",
+        default_endpoint_template="foo.{UNIVERSE_DOMAIN}",
+    )
+    assert endpoint == "foo.mtls.googleapis.com"
+
+
+def test__get_api_endpoint_mtls_auto_no_cert():
+    # "auto" without client_cert_source should use the default template
+    endpoint = client_helpers._get_api_endpoint(
+        api_override=None,
+        client_cert_source=None,
+        universe_domain="googleapis.com",
+        use_mtls_endpoint="auto",
+        default_universe="googleapis.com",
+        default_mtls_endpoint="foo.mtls.googleapis.com",
+        default_endpoint_template="foo.{UNIVERSE_DOMAIN}",
+    )
+    assert endpoint == "foo.googleapis.com"
+
+
+def test__get_api_endpoint_mtls_universe_mismatch():
+    # mTLS is only supported in the default universe
+    with pytest.raises(MutualTLSChannelError, match="mTLS is not supported"):
+        client_helpers._get_api_endpoint(
+            api_override=None,
+            client_cert_source=mock.Mock(),
+            universe_domain="custom-universe.com",
+            use_mtls_endpoint="auto",
+            default_universe="googleapis.com",
+            default_mtls_endpoint="foo.mtls.googleapis.com",
+            default_endpoint_template="foo.{UNIVERSE_DOMAIN}",
+        )