feat(bigquery): add bigquery_call_procedure sample to call a SQL stored procedure (#14730)

Problem:
The BigQuery documentation (https://cloud.google.com/bigquery/docs/procedures)
needs a standalone, tested Python code sample demonstrating how to
call a SQL stored procedure (region tag `bigquery_call_procedure`).

Solution:
- Add `call_procedure(project_id: str, dataset_id: str, procedure_id: str) -> None` in `bigquery/stored_procedures/bigquery_call_procedure.py`
  (Invoke a BigQuery SQL stored procedure with input parameters and capture its output variable using CALL.)
- Add unit tests (`bigquery/stored_procedures/bigquery_call_procedure_test.py`) covering both the success
  path and API error handling (`GoogleAPICallError`)

Author: iennae

bigquery/stored_procedures/bigquery_call_procedure.py

@@ -0,0 +1,77 @@
+# 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
+#
+#     https://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.
+
+# [START bigquery_call_procedure]
+import sys
+
+from google.api_core import exceptions
+from google.cloud import bigquery
+
+
+def call_procedure(
+    project_id: str,
+    dataset_id: str,
+    procedure_id: str,
+) -> None:
+    """Calls a GoogleSQL stored procedure with input and output parameters.
+
+    Args:
+        project_id: Google Cloud project ID (for example, 'example-project').
+        dataset_id: BigQuery dataset ID containing the stored procedure
+            (for example, 'example_dataset').
+        procedure_id: Stored procedure ID to invoke
+            (for example, 'example_procedure').
+    """
+    client = bigquery.Client(project=project_id)
+    routine_ref = f"{project_id}.{dataset_id}.{procedure_id}"
+    # Bind the input filter value via a query parameter to prevent SQL injection.
+    target_corpus = "hamlet"
+    job_config = bigquery.QueryJobConfig(
+        query_parameters=[
+            bigquery.ScalarQueryParameter("target_corpus", "STRING", target_corpus),
+        ]
+    )
+    sql = f"""
+        DECLARE out_total INT64;
+        CALL `{routine_ref}`(@target_corpus, out_total);
+        SELECT out_total AS total_words;
+    """
+
+    try:
+        print(f"Calling stored procedure: {routine_ref}")
+        query_job = client.query(sql, job_config=job_config)
+        rows = list(query_job.result())
+    except exceptions.NotFound as err:
+        print(
+            f"error: stored procedure '{procedure_id}' not found in dataset "
+            f"'{dataset_id}' for project '{project_id}': {err.message}",
+            file=sys.stderr,
+        )
+        return
+    except exceptions.GoogleAPICallError as err:
+        print(
+            f"error: failed to call stored procedure '{procedure_id}' in dataset "
+            f"'{dataset_id}' for project '{project_id}': {err.message}",
+            file=sys.stderr,
+        )
+        return
+
+    total_words = rows[0].total_words if rows else 0
+    print(f"Resource ID: {routine_ref}")
+    print(f"Corpus: {target_corpus}")
+    print(f"Job ID: {query_job.job_id}")
+    print(f"Total Words: {total_words}")
+
+
+# [END bigquery_call_procedure]

bigquery/stored_procedures/bigquery_call_procedure_test.py

@@ -0,0 +1,71 @@
+# 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
+#
+#     https://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.
+
+from unittest import mock
+
+import bigquery_call_procedure
+from google.api_core import exceptions
+import pytest
+
+
+def test_call_procedure_success(
+    monkeypatch: pytest.MonkeyPatch,
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    mock_client = mock.MagicMock()
+    mock_job = mock.MagicMock()
+    mock_job.job_id = "example-job-123"
+    mock_row = mock.MagicMock()
+    mock_row.total_words = 42
+    mock_job.result.return_value = [mock_row]
+    mock_client.query.return_value = mock_job
+    monkeypatch.setattr(
+        bigquery_call_procedure.bigquery,
+        "Client",
+        lambda project=None: mock_client,
+    )
+
+    bigquery_call_procedure.call_procedure(
+        project_id="example-project",
+        dataset_id="example_dataset",
+        procedure_id="example_procedure",
+    )
+
+    captured = capsys.readouterr()
+    assert "Resource ID:" in captured.out
+    assert "example-project" in captured.out
+    assert mock_client.query.called
+
+
+def test_call_procedure_error(
+    monkeypatch: pytest.MonkeyPatch,
+    capsys: pytest.CaptureFixture[str],
+) -> None:
+    mock_client = mock.MagicMock()
+    mock_client.query.side_effect = exceptions.NotFound("resource error")
+    monkeypatch.setattr(
+        bigquery_call_procedure.bigquery,
+        "Client",
+        lambda project=None: mock_client,
+    )
+
+    bigquery_call_procedure.call_procedure(
+        project_id="example-project",
+        dataset_id="example_dataset",
+        procedure_id="example_procedure",
+    )
+
+    captured = capsys.readouterr()
+    assert "error:" in captured.err
+    assert "example-project" in captured.err

bigquery/stored_procedures/noxfile_config.py

@@ -0,0 +1,23 @@
+# 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
+#
+#     https://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.
+
+TEST_CONFIG_OVERRIDE = {
+    # You can opt out from the test for specific Python versions.
+    "ignored_versions": ["2.7", "3.7", "3.8", "3.9", "3.10", "3.11"],
+    # Enforce type hints on new samples.
+    "enforce_type_hints": True,
+    "gcloud_project_env": "GOOGLE_CLOUD_PROJECT",
+    "pip_version_override": None,
+    "envs": {},
+}

bigquery/stored_procedures/requirements-test.txt

@@ -0,0 +1 @@
+pytest==9.0.3; python_version >= "3.10"

bigquery/stored_procedures/requirements.txt

@@ -0,0 +1 @@
+google-cloud-bigquery==3.47.0