Add the drop replication slot functionality

replication.go

@@ -362,7 +362,7 @@ func (rc *ReplicationConn) CreateReplicationSlot(slotName, outputPlugin string)
 }
 
 // Drop the replication slot for the given name
-func (rc *ReplicationConn) DropReplicationSlot(slotName, outputPlugin string) (err error) {
+func (rc *ReplicationConn) DropReplicationSlot(slotName string) (err error) {
 	_, err = rc.c.Exec(fmt.Sprintf("DROP_REPLICATION_SLOT %s", slotName))
 	return
 }

replication_test.go

@@ -173,6 +173,10 @@ func TestSimpleReplicationConnection(t *testing.T) {
 		t.Errorf("Unexpected write position %d", status.WalWritePosition)
 	}
 
+	err = replicationConn.DropReplicationSlot("pgx_test")
+	if err != nil {
+		t.Fatalf("Failed to drop replication slot %v", err)
+	}
 	err = replicationConn.Close()
 	if err != nil {
 		t.Fatalf("Replication connection close failed: %v", err)
@@ -183,10 +187,4 @@ func TestSimpleReplicationConnection(t *testing.T) {
 	if integerRestartLsn != maxWal {
 		t.Fatalf("Wal offset update failed, expected %s found %s", pgx.FormatLSN(maxWal), restartLsn)
 	}
-
-	_, err = conn.Exec("select pg_drop_replication_slot($1)", "pgx_test")
-	if err != nil {
-		t.Fatalf("Failed to drop replication slot: %v", err)
-	}
-
 }