Add AstraDB document loader (#14747)

- **Description:** this adds the AstraDB document loader and an
integration test
  - **Twitter handle:** cbornet_

libs/community/tests/integration_tests/document_loaders/test_astradb.py

@@ -0,0 +1,96 @@
+"""
+Test of Astra DB document loader class `AstraDBLoader`
+
+Required to run this test:
+    - a recent `astrapy` Python package available
+    - an Astra DB instance;
+    - the two environment variables set:
+        export ASTRA_DB_API_ENDPOINT="https://<DB-ID>-us-east1.apps.astra.datastax.com"
+        export ASTRA_DB_APPLICATION_TOKEN="AstraCS:........."
+    - optionally this as well (otherwise defaults are used):
+        export ASTRA_DB_KEYSPACE="my_keyspace"
+"""
+import json
+import os
+import uuid
+
+import pytest
+
+from langchain_community.document_loaders.astradb import AstraDBLoader
+
+ASTRA_DB_APPLICATION_TOKEN = os.getenv("ASTRA_DB_APPLICATION_TOKEN")
+ASTRA_DB_API_ENDPOINT = os.getenv("ASTRA_DB_API_ENDPOINT")
+ASTRA_DB_KEYSPACE = os.getenv("ASTRA_DB_KEYSPACE")
+
+
+def _has_env_vars() -> bool:
+    return all([ASTRA_DB_APPLICATION_TOKEN, ASTRA_DB_API_ENDPOINT])
+
+
+@pytest.fixture
+def astra_db_collection():
+    from astrapy.db import AstraDB
+
+    astra_db = AstraDB(
+        token=ASTRA_DB_APPLICATION_TOKEN,
+        api_endpoint=ASTRA_DB_API_ENDPOINT,
+        namespace=ASTRA_DB_KEYSPACE,
+    )
+    collection_name = f"lc_test_loader_{str(uuid.uuid4()).split('-')[0]}"
+    collection = astra_db.create_collection(collection_name)
+
+    yield collection
+
+    astra_db.delete_collection(collection_name)
+
+
+@pytest.mark.requires("astrapy")
+@pytest.mark.skipif(not _has_env_vars(), reason="Missing Astra DB env. vars")
+class TestAstraDB:
+    def test_astradb_loader(self, astra_db_collection) -> None:
+        astra_db_collection.insert_many([{"foo": "bar", "baz": "qux"}] * 20)
+        astra_db_collection.insert_many(
+            [{"foo": "bar2", "baz": "qux"}] * 4 + [{"foo": "bar", "baz": "qux"}] * 4
+        )
+
+        loader = AstraDBLoader(
+            astra_db_collection.collection_name,
+            token=ASTRA_DB_APPLICATION_TOKEN,
+            api_endpoint=ASTRA_DB_API_ENDPOINT,
+            namespace=ASTRA_DB_KEYSPACE,
+            nb_prefetched=1,
+            projection={"foo": 1},
+            find_options={"limit": 22},
+            filter_criteria={"foo": "bar"},
+        )
+        docs = loader.load()
+
+        assert len(docs) == 22
+        ids = set()
+        for doc in docs:
+            content = json.loads(doc.page_content)
+            assert content["foo"] == "bar"
+            assert "baz" not in content
+            assert content["_id"] not in ids
+            ids.add(content["_id"])
+            assert doc.metadata == {
+                "namespace": astra_db_collection.astra_db.namespace,
+                "api_endpoint": astra_db_collection.astra_db.base_url,
+                "collection": astra_db_collection.collection_name,
+            }
+
+    def test_extraction_function(self, astra_db_collection) -> None:
+        astra_db_collection.insert_many([{"foo": "bar", "baz": "qux"}] * 20)
+
+        loader = AstraDBLoader(
+            astra_db_collection.collection_name,
+            token=ASTRA_DB_APPLICATION_TOKEN,
+            api_endpoint=ASTRA_DB_API_ENDPOINT,
+            namespace=ASTRA_DB_KEYSPACE,
+            find_options={"limit": 30},
+            extraction_function=lambda x: x["foo"],
+        )
+        docs = loader.lazy_load()
+        doc = next(docs)
+
+        assert doc.page_content == "bar"