Add test coverage for optional BigQuery dependency

libs/community/langchain_google_community/bigquery.py

@@ -1,16 +1,24 @@
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, List, Optional
+from typing import TYPE_CHECKING, List, Optional, Any
 
 from langchain_core.document_loaders import BaseLoader
 from langchain_core.documents import Document
+from langchain_core.utils import guard_import
 
 from langchain_google_community._utils import get_client_info
 
 if TYPE_CHECKING:
     from google.auth.credentials import Credentials  # type: ignore[import]
 
 
+def import_bigquery() -> Any:
+    """Import the google-cloud-bigquery library and return the client."""
+    return guard_import(
+        "google.cloud.bigquery", pip_name="langchain-google-community[bigquery]"
+    )
+
+
 class BigQueryLoader(BaseLoader):
     """Load from the Google Cloud Platform `BigQuery`.
 
@@ -44,6 +52,7 @@ def __init__(
                 (`google.auth.compute_engine.Credentials`) or Service Account
                 (`google.oauth2.service_account.Credentials`) credentials directly.
         """
+        import_bigquery()
         self.query = query
         self.project = project
         self.page_content_columns = page_content_columns
@@ -92,4 +101,4 @@ def load(self) -> List[Document]:
             doc = Document(page_content=page_content, metadata=metadata)
             docs.append(doc)
 
-        return docs
+        return docs

libs/community/tests/unit_tests/test_bigquery.py

@@ -0,0 +1,24 @@
+"""Unit tests for the BigQueryLoader."""
+import pytest
+from unittest.mock import patch
+
+from langchain_google_community.bigquery import BigQueryLoader
+
+
+@patch("langchain_google_community.bigquery.import_bigquery")
+def test_bigquery_loader_import_error(mock_import_bigquery):
+    """Test that BigQueryLoader raises an ImportError if google-cloud-bigquery is not installed."""
+    # Simulate the ImportError that occurs when the dependency is missing
+    mock_import_bigquery.side_effect = ImportError(
+        "Could not import google.cloud.bigquery python package. "
+        "Please, install it with `pip install langchain-google-community[bigquery]`"
+    )
+
+    with pytest.raises(ImportError) as excinfo:
+        BigQueryLoader(query="SELECT 1")
+
+    assert "Could not import google.cloud.bigquery python package." in str(excinfo.value)
+    assert (
+        "Please, install it with `pip install langchain-google-community[bigquery]`"
+        in str(excinfo.value)
+    )