Parsed test spec with 3 sessions

starting permutation: s2b s2txid s1init s3b s3txid s2alter s2c s2b s2txid s3c s2c s1insert s1checkpoint s1start s1insert s1alter s1insert s1start
step s2b: BEGIN;
step s2txid: SELECT pg_current_xact_id() IS NULL;
?column?
--------
f       
(1 row)

step s1init: SELECT 'init' FROM pg_create_logical_replication_slot('isolation_slot', 'test_decoding'); <waiting ...>
step s3b: BEGIN;
step s3txid: SELECT pg_current_xact_id() IS NULL;
?column?
--------
f       
(1 row)

step s2alter: ALTER TABLE do_write ADD COLUMN addedbys2 int;
step s2c: COMMIT;
step s2b: BEGIN;
step s2txid: SELECT pg_current_xact_id() IS NULL;
?column?
--------
f       
(1 row)

step s3c: COMMIT;
step s1init: <... completed>
?column?
--------
init    
(1 row)

step s2c: COMMIT;
step s1insert: INSERT INTO do_write DEFAULT VALUES;
step s1checkpoint: CHECKPOINT;
step s1start: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'include-xids', 'false');
data                                                                
--------------------------------------------------------------------
BEGIN                                                               
table public.do_write: INSERT: id[integer]:1 addedbys2[integer]:null
COMMIT                                                              
(3 rows)

step s1insert: INSERT INTO do_write DEFAULT VALUES;
step s1alter: ALTER TABLE do_write ADD COLUMN addedbys1 int;
step s1insert: INSERT INTO do_write DEFAULT VALUES;
step s1start: SELECT data FROM pg_logical_slot_get_changes('isolation_slot', NULL, NULL, 'include-xids', 'false');
data                                                                                        
--------------------------------------------------------------------------------------------
BEGIN                                                                                       
table public.do_write: INSERT: id[integer]:2 addedbys2[integer]:null                        
COMMIT                                                                                      
BEGIN                                                                                       
COMMIT                                                                                      
BEGIN                                                                                       
table public.do_write: INSERT: id[integer]:3 addedbys2[integer]:null addedbys1[integer]:null
COMMIT                                                                                      
(8 rows)

?column?
--------
stop    
(1 row)