Fix debug task for BigQuery connections

CHANGELOG.md

@@ -8,6 +8,7 @@
 - Fix unique_id generation for generic tests so tests with the same FQN but different configuration will run. ([#3254](https://github.com/fishtown-analytics/dbt/issues/3254), [#3335](https://github.com/fishtown-analytics/dbt/issues/3335))
 - Update the snowflake adapter to only comment on a column if it exists when using the persist_docs config ([#3039](https://github.com/fishtown-analytics/dbt/issues/3039), [#3149](https://github.com/fishtown-analytics/dbt/pull/3149))
 - Separate `compiled_path` from `build_path`, and print the former alongside node error messages ([#1985](https://github.com/fishtown-analytics/dbt/issues/1985), [#3327](https://github.com/fishtown-analytics/dbt/pull/3327))
+- Fix exception caused when running `dbt debug` with BigQuery connections ([#3314](https://github.com/fishtown-analytics/dbt/issues/3314), [#3351](https://github.com/fishtown-analytics/dbt/pull/3351))
 
 ### Under the hood
 - Added logic for registry requests to raise a timeout error after a response hangs out for 30 seconds and 5 attempts have been made to reach the endpoint ([#3177](https://github.com/fishtown-analytics/dbt/issues/3177), [#3275](https://github.com/fishtown-analytics/dbt/pull/3275))

plugins/bigquery/dbt/adapters/bigquery/connections.py

@@ -309,7 +309,7 @@ def raw_execute(self, sql, fetch=False, *, use_legacy_sql=False):
 
         logger.debug('On {}: {}', conn.name, sql)
 
-        if self.profile.query_comment.job_label:
+        if self.profile.query_comment and self.profile.query_comment.job_label:
             query_comment = self.query_header.comment.query_comment
             labels = self._labels_from_query_comment(query_comment)
         else:

test/integration/049_dbt_debug_test/test_debug.py

@@ -64,6 +64,11 @@ def test_postgres_ok(self):
         self.run_dbt(['debug'])
         self.assertNotIn('ERROR', self.capsys.readouterr().out)
 
+    @use_profile('bigquery')
+    def test_bigquery_ok(self):
+        self.run_dbt(['debug'])
+        self.assertNotIn('ERROR', self.capsys.readouterr().out)
+
     @use_profile('postgres')
     def test_postgres_nopass(self):
         self.run_dbt(['debug', '--target', 'nopass'], expect_pass=False)