fix: populate default timeout and retry after client-side timeout (#896)

This addresses internal issue 195337762 where sometimes query job creation can
take longer than expected and retrying the API call can be faster than waiting
for the first query job request to fail.

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Fixes #889
Towards #779

 🦕

Author: tswast

google/cloud/bigquery/client.py

@@ -29,6 +29,7 @@
     exceptions.BadGateway,
     requests.exceptions.ChunkedEncodingError,
     requests.exceptions.ConnectionError,
+    requests.exceptions.Timeout,
     auth_exceptions.TransportError,
 )
 
@@ -59,6 +60,13 @@ def _should_retry(exc):
 pass ``retry=bigquery.DEFAULT_RETRY.with_deadline(30)``.
 """
 
+DEFAULT_TIMEOUT = 5.0 * 60.0
+"""The default API timeout.
+
+This is the time to wait per request. To adjust the total wait time, set a
+deadline on the retry object.
+"""
+
 job_retry_reasons = "rateLimitExceeded", "backendError"
 
 

google/cloud/bigquery/retry.py

@@ -160,10 +160,6 @@ def snippets(session):
     if os.environ.get("RUN_SNIPPETS_TESTS", "true") == "false":
         session.skip("RUN_SNIPPETS_TESTS is set to false, skipping")
 
-    # Sanity check: Only run snippets tests if the environment variable is set.
-    if not os.environ.get("GOOGLE_APPLICATION_CREDENTIALS", ""):
-        session.skip("Credentials must be set via environment variable.")
-
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )