Tests now connect to DBs only if being run (instead of on the module level)

Author: erezsh

tests/common.py

@@ -63,12 +63,17 @@ def get_git_revision_short_hash() -> str:
     db.Trino: TEST_TRINO_CONN_STRING,
 }
 
-for k, v in CONN_STRINGS.items():
-    if v is None:
-        logging.warn(f"Connection to {k} not configured")
-    else:
-        logging.info(f"Testing database: {k}")
 
+def _print_used_dbs():
+    used = {k.__name__ for k, v in CONN_STRINGS.items() if v is not None}
+    unused = {k.__name__ for k, v in CONN_STRINGS.items() if v is None}
+
+    logging.info(f"Testing databases: {', '.join(used)}")
+    if unused:
+        logging.info(f"Connection not configured; skipping tests for: {', '.join(unused)}")
+
+
+_print_used_dbs()
 CONN_STRINGS = {k: v for k, v in CONN_STRINGS.items() if v is not None}
 
 

tests/test_database_types.py

@@ -26,11 +26,18 @@
     _drop_table_if_exists,
 )
 
+CONNS = None
 
-CONNS = {k: db.connect.connect(v, N_THREADS) for k, v in CONN_STRINGS.items()}
 
-CONNS[db.MySQL].query("SET @@session.time_zone='+00:00'", None)
-oracle.SESSION_TIME_ZONE = postgresql.SESSION_TIME_ZONE = "UTC"
+def init_conns():
+    global CONNS
+    if CONNS is not None:
+        return
+
+    CONNS = {k: db.connect.connect(v, N_THREADS) for k, v in CONN_STRINGS.items()}
+    CONNS[db.MySQL].query("SET @@session.time_zone='+00:00'", None)
+    oracle.SESSION_TIME_ZONE = postgresql.SESSION_TIME_ZONE = "UTC"
+
 
 DATABASE_TYPES = {
     db.PostgreSQL: {
@@ -374,7 +381,7 @@ def __iter__(self):
         ) in source_type_categories.items():  # int, datetime, ..
             for source_type in source_types:
                 for target_type in target_type_categories[type_category]:
-                    if CONNS.get(source_db, False) and CONNS.get(target_db, False):
+                    if CONN_STRINGS.get(source_db, False) and CONN_STRINGS.get(target_db, False):
                         type_pairs.append(
                             (
                                 source_db,
@@ -518,6 +525,9 @@ def _create_table_with_indexes(conn, table, type):
 class TestDiffCrossDatabaseTables(unittest.TestCase):
     maxDiff = 10000
 
+    def setUp(self) -> None:
+        init_conns()
+
     def tearDown(self) -> None:
         if not BENCHMARK:
             _drop_table_if_exists(self.src_conn, self.src_table)

tests/test_diff_tables.py

@@ -20,8 +20,17 @@
     N_THREADS,
 )
 
+DATABASE_INSTANCES = None
 DATABASE_URIS = {k.__name__: v for k, v in CONN_STRINGS.items()}
-DATABASE_INSTANCES = {k.__name__: connect(v, N_THREADS) for k, v in CONN_STRINGS.items()}
+
+
+def init_instances():
+    global DATABASE_INSTANCES
+    if DATABASE_INSTANCES is not None:
+        return
+
+    DATABASE_INSTANCES = {k.__name__: connect(v, N_THREADS) for k, v in CONN_STRINGS.items()}
+
 
 TEST_DATABASES = {x.__name__ for x in (db.MySQL, db.PostgreSQL, db.Oracle, db.Redshift, db.Snowflake, db.BigQuery)}
 
@@ -80,6 +89,7 @@ class TestPerDatabase(unittest.TestCase):
 
     def setUp(self):
         assert self.db_name
+        init_instances()
 
         self.connection = DATABASE_INSTANCES[self.db_name]
         if self.with_preql: