When creating new physical replication slot check that it doesn't already exist

Author: zilder

testgres/node.py

@@ -49,7 +49,8 @@
     ExecUtilException,  \
     QueryException,     \
     StartNodeException, \
-    TimeoutException
+    TimeoutException,   \
+    TestgresException
 
 from .logger import TestgresLogger
 
@@ -263,6 +264,13 @@ def _create_replication_slot(self, slot_name, dbname=None, username=None):
             dbname: database name
             username: database user name
         """
+        rs = self.execute("select exists (select * from pg_replication_slots "
+                          "where slot_name = '{}')".format(slot_name),
+                          dbname=dbname, username=username)
+
+        if rs[0][0]:
+            raise TestgresException("Slot '{}' already exists".format(slot_name))
+
         query = (
             "select pg_create_physical_replication_slot('{}')"
         ).format(slot_name)

tests/test_simple.py

@@ -21,7 +21,8 @@
     BackupException, \
     QueryException, \
     CatchUpException, \
-    TimeoutException
+    TimeoutException, \
+    TestgresException
 
 from testgres import \
     TestgresConfig, \
@@ -393,6 +394,10 @@ def test_replication_slots(self):
                 res = replica.execute('select * from test')
                 self.assertListEqual(res, [(1, ), (2, )])
 
+                # cannot create new slot with the same name
+                with self.assertRaises(TestgresException):
+                    node._create_replication_slot('slot1')
+
     def test_incorrect_catchup(self):
         with get_new_node() as node:
             node.init(allow_streaming=True).start()