detect-pdf update [(#1460)](GoogleCloudPlatform/python-docs-samples#1460)

* detect-pdf update

* update test

Author: dizcology

samples/snippets/detect/detect_pdf_test.py

@@ -25,14 +25,17 @@
 
 
 def test_async_detect_document(capsys):
+    storage_client = storage.Client()
+    bucket = storage_client.get_bucket(BUCKET)
+    assert len(list(bucket.list_blobs(prefix=OUTPUT_PREFIX))) == 0
+
     async_detect_document(
         gcs_source_uri=GCS_SOURCE_URI,
         gcs_destination_uri=GCS_DESTINATION_URI)
     out, _ = capsys.readouterr()
 
     assert 'Hodge conjecture' in out
+    assert len(list(bucket.list_blobs(prefix=OUTPUT_PREFIX))) == 3
 
-    storage_client = storage.Client()
-    bucket = storage_client.get_bucket(BUCKET)
     for blob in bucket.list_blobs(prefix=OUTPUT_PREFIX):
         blob.delete()

samples/snippets/detect/requirements.txt

@@ -1,2 +1,2 @@
-google-cloud-vision==0.30.1
+google-cloud-vision==0.31.0
 google-cloud-storage==1.6.0