Parsed test spec with 3 sessions

starting permutation: wx1 wx2 c1 c2 read
step wx1: UPDATE accounts SET balance = balance - 200 WHERE accountid = 'checking';
step wx2: UPDATE accounts SET balance = balance + 450 WHERE accountid = 'checking'; <waiting ...>
step c1: COMMIT;
step wx2: <... completed>
step c2: COMMIT;
step read: SELECT * FROM accounts ORDER BY accountid;
accountid      balance        

checking       850            
savings        600            

starting permutation: wy1 wy2 c1 c2 read
step wy1: UPDATE accounts SET balance = balance + 500 WHERE accountid = 'checking';
step wy2: UPDATE accounts SET balance = balance + 1000 WHERE accountid = 'checking' AND balance < 1000; <waiting ...>
step c1: COMMIT;
step wy2: <... completed>
step c2: COMMIT;
step read: SELECT * FROM accounts ORDER BY accountid;
accountid      balance        

checking       1100           
savings        600            

starting permutation: upsert1 upsert2 c1 c2 read
step upsert1: 
	WITH upsert AS
	  (UPDATE accounts SET balance = balance + 500
	   WHERE accountid = 'savings'
	   RETURNING accountid)
	INSERT INTO accounts SELECT 'savings', 500
	  WHERE NOT EXISTS (SELECT 1 FROM upsert);

step upsert2: 
	WITH upsert AS
	  (UPDATE accounts SET balance = balance + 1234
	   WHERE accountid = 'savings'
	   RETURNING accountid)
	INSERT INTO accounts SELECT 'savings', 1234
	  WHERE NOT EXISTS (SELECT 1 FROM upsert);
 <waiting ...>
step c1: COMMIT;
step upsert2: <... completed>
step c2: COMMIT;
step read: SELECT * FROM accounts ORDER BY accountid;
accountid      balance        

checking       600            
savings        2334