Handle external bigquery relations (#791)

CHANGELOG.md

@@ -2,6 +2,9 @@
 
 ### Changes
 
+ - Support external BigQuery relations ([#828](https://github.com/fishtown-analytics/dbt/pull/828))
+ - Added tox environments that have the user specify what tests should be run ([#837](https://github.com/fishtown-analytics/dbt/pull/837))
+ - Set the TCP keepalive on redshift ([#826](https://github.com/fishtown-analytics/dbt/pull/826))
  - Fix the error handling for profiles.yml validation ([#820](https://github.com/fishtown-analytics/dbt/pull/820))
  - Make the `--threads` parameter actually change the number of threads used ([#819](https://github.com/fishtown-analytics/dbt/pull/819))
  - Use Mapping instead of dict as the base class for APIObject ([#756](https://github.com/fishtown-analytics/dbt/pull/756))

dbt/adapters/bigquery/relation.py

@@ -3,6 +3,7 @@
 
 
 class BigQueryRelation(DefaultRelation):
+    External = "external"
 
     DEFAULTS = {
         'metadata': {
@@ -54,7 +55,7 @@ class BigQueryRelation(DefaultRelation):
                 },
             },
             'type': {
-                'enum': DefaultRelation.RelationTypes + [None],
+                'enum': DefaultRelation.RelationTypes + [External, None],
             },
             'path': PATH_SCHEMA,
             'include_policy': POLICY_SCHEMA,

test/unit/test_bigquery_adapter.py

@@ -4,6 +4,7 @@
 import dbt.flags as flags
 
 from dbt.adapters.bigquery import BigQueryAdapter
+from dbt.adapters.bigquery.relation import BigQueryRelation
 import dbt.exceptions
 from dbt.logger import GLOBAL_LOGGER as logger  # noqa
 
@@ -58,3 +59,88 @@ def test_acquire_connection_service_account_validations(self, mock_open_connecti
             self.fail('validation failed with unknown exception: {}'.format(str(e)))
 
         mock_open_connection.assert_called_once()
+
+
+class TestBigQueryRelation(unittest.TestCase):
+    def setUp(self):
+        flags.STRICT_MODE = True
+
+    def test_view_temp_relation(self):
+        kwargs = {
+            'type': None,
+            'path': {
+                'project': 'test-project',
+                'schema': 'test_schema',
+                'identifier': 'my_view'
+            },
+            'table_name': 'my_view__dbt_tmp',
+            'quote_policy': {
+                'identifier': False
+            }
+        }
+        BigQueryRelation(**kwargs)
+
+    def test_view_relation(self):
+        kwargs = {
+            'type': 'view',
+            'path': {
+                'project': 'test-project',
+                'schema': 'test_schema',
+                'identifier': 'my_view'
+            },
+            'table_name': 'my_view',
+            'quote_policy': {
+                'identifier': True,
+                'schema': True
+            }
+        }
+        BigQueryRelation(**kwargs)
+
+    def test_table_relation(self):
+        kwargs = {
+            'type': 'table',
+            'path': {
+                'project': 'test-project',
+                'schema': 'test_schema',
+                'identifier': 'generic_table'
+            },
+            'table_name': 'generic_table',
+            'quote_policy': {
+                'identifier': True,
+                'schema': True
+            }
+        }
+        BigQueryRelation(**kwargs)
+
+    def test_external_source_relation(self):
+        kwargs = {
+            'type': 'external',
+            'path': {
+                'project': 'test-project',
+                'schema': 'test_schema',
+                'identifier': 'sheet'
+            },
+            'table_name': 'sheet',
+            'quote_policy': {
+                'identifier': True,
+                'schema': True
+            }
+        }
+        BigQueryRelation(**kwargs)
+
+    def test_invalid_relation(self):
+        kwargs = {
+            'type': 'invalid-type',
+            'path': {
+                'project': 'test-project',
+                'schema': 'test_schema',
+                'identifier': 'my_invalid_id'
+            },
+            'table_name': 'my_invalid_id',
+            'quote_policy': {
+                'identifier': False,
+                'schema': True
+            }
+        }
+        with self.assertRaises(dbt.exceptions.ValidationException):
+            BigQueryRelation(**kwargs)