test: add comprehensive unit tests for PandasGBQVersions to fix coverage

Author: shuoweil

packages/google-cloud-bigquery/tests/unit/test__versions_helpers.py

@@ -31,8 +31,7 @@
 except ImportError:
     pandas = None
 
-from google.cloud.bigquery import _versions_helpers
-from google.cloud.bigquery import exceptions
+from google.cloud.bigquery import _versions_helpers, exceptions
 
 
 @pytest.mark.skipif(pyarrow is None, reason="pyarrow is not installed")
@@ -246,3 +245,102 @@ def test_installed_pandas_version_returns_parsed_version():
     assert version.major == 1
     assert version.minor == 1
     assert version.micro == 0
+
+
+def test_installed_pandas_gbq_version_returns_cached():
+    versions = _versions_helpers.PandasGBQVersions()
+    versions._installed_version = object()
+    assert versions.installed_version is versions._installed_version
+
+
+def test_installed_pandas_gbq_version_returns_parsed_version():
+    import sys
+    mock_pandas_gbq = mock.Mock()
+    mock_pandas_gbq.__version__ = "1.2.3"
+    versions = _versions_helpers.PandasGBQVersions()
+    with mock.patch.dict(sys.modules, {"pandas_gbq": mock_pandas_gbq}):
+        version = versions.installed_version
+
+    assert version.major == 1
+    assert version.minor == 2
+    assert version.micro == 3
+
+
+def test_installed_pandas_gbq_version_falls_back_on_import_error():
+    import sys
+    versions = _versions_helpers.PandasGBQVersions()
+    with mock.patch.dict(sys.modules, {"pandas_gbq": None}):
+        version = versions.installed_version
+
+    assert version.major == 0
+    assert version.minor == 0
+    assert version.micro == 0
+
+
+def test_installed_pandas_gbq_version_falls_back_on_other_error():
+    import sys
+    # Simulate a corrupted package raising an error on import/property access
+    class CorruptPandasGBQ:
+        @property
+        def __version__(self):
+            raise TypeError("Corrupted package")
+
+    versions = _versions_helpers.PandasGBQVersions()
+    with mock.patch.dict(sys.modules, {"pandas_gbq": CorruptPandasGBQ()}):
+        version = versions.installed_version
+
+    assert version.major == 0
+    assert version.minor == 0
+    assert version.micro == 0
+
+
+def test_pandas_gbq_delegation_api_version_returns_cached():
+    versions = _versions_helpers.PandasGBQVersions()
+    versions._delegation_api_version = object()
+    assert versions.delegation_api_version is versions._delegation_api_version
+
+
+def test_pandas_gbq_delegation_api_version_returns_value():
+    import sys
+    mock_pandas_gbq = mock.Mock()
+    mock_pandas_gbq._internal_delegation_api_version = 42
+    versions = _versions_helpers.PandasGBQVersions()
+    with mock.patch.dict(sys.modules, {"pandas_gbq": mock_pandas_gbq}):
+        version = versions.delegation_api_version
+
+    assert version == 42
+
+
+def test_pandas_gbq_delegation_api_version_falls_back_on_import_error():
+    import sys
+    versions = _versions_helpers.PandasGBQVersions()
+    with mock.patch.dict(sys.modules, {"pandas_gbq": None}):
+        version = versions.delegation_api_version
+
+    assert version == 0
+
+
+def test_pandas_gbq_delegation_api_version_falls_back_on_other_error():
+    import sys
+    class CorruptPandasGBQ:
+        @property
+        def _internal_delegation_api_version(self):
+            raise TypeError("Corrupted package")
+
+    versions = _versions_helpers.PandasGBQVersions()
+    with mock.patch.dict(sys.modules, {"pandas_gbq": CorruptPandasGBQ()}):
+        version = versions.delegation_api_version
+
+    assert version == 0
+
+
+def test_pandas_gbq_is_delegation_supported_true():
+    versions = _versions_helpers.PandasGBQVersions()
+    versions._delegation_api_version = 1
+    assert versions.is_delegation_supported is True
+
+
+def test_pandas_gbq_is_delegation_supported_false():
+    versions = _versions_helpers.PandasGBQVersions()
+    versions._delegation_api_version = 0
+    assert versions.is_delegation_supported is False