Parsed test spec with 3 sessions

starting permutation: s1a s2a s3a s1b s2b s3b
step s1a: SELECT * FROM foo FOR UPDATE;
id|data
--+----
 1|x   
(1 row)

step s2a: SELECT * FROM foo FOR UPDATE; <waiting ...>
step s3a: SELECT * FROM foo FOR UPDATE NOWAIT;
ERROR:  could not obtain lock on row in relation "foo"
step s1b: COMMIT;
step s2a: <... completed>
id|data
--+----
 1|x   
(1 row)

step s2b: COMMIT;
step s3b: COMMIT;