integration test for DocAI parser (#11424)

- **Description:** added an integration test
  - **Issue:** #11407 

@baskaryan

libs/langchain/tests/integration_tests/document_loaders/parsers/test_docai.py

@@ -0,0 +1,36 @@
+"""Test Google Cloud DocAI parser.
+
+You need to create a processor and enable the DocAI before running this test:
+
+https://cloud.google.com/document-ai/docs/setup
+"""
+import os
+
+from langchain.document_loaders.blob_loaders import Blob
+from langchain.document_loaders.parsers import DocAIParser
+from langchain.schema import Document
+
+
+def test_docai_parser() -> None:
+    """In order to run this test, you should provide a processor name, output path
+        for DocAI to store parsing results, and an input blob path to parse.
+
+    Example:
+    export BLOB_PATH=gs://...
+    export GCS_OUTPUT_PATH=gs://...
+    export PROCESSOR_NAME=projects/.../locations/us/processors/...
+    """
+    blob_path = os.environ["BLOB_PATH"]
+    gcs_output_path = os.environ["GCS_OUTPUT_PATH"]
+    processor_name = os.environ["PROCESSOR_NAME"]
+    parser = DocAIParser(
+        location="us", processor_name=processor_name, gcs_output_path=gcs_output_path
+    )
+    blob = Blob(path=blob_path)
+    documents = list(parser.lazy_parse(blob))
+    assert len(documents) > 0
+    for i, doc in enumerate(documents):
+        assert isinstance(doc, Document)
+        assert doc.page_content
+        assert doc.metadata["source"] == blob_path
+        assert doc.metadata["page"] == i + 1