Add simple tests of EvalPlanQual using the isolationtester infrastructure.

Much more could be done here, but at least now we have *some* automated
test coverage of that mechanism.  In particular this tests the writable-CTE
case reported by Phil Sorber.

In passing, remove isolationtester's arbitrary restriction on the number of
steps in a permutation list.  I used this so that a single spec file could
be used to run several related test scenarios, but there are other possible
reasons to want a step series that's not exactly a permutation.  Improve
documentation and fix a couple other nits as well.

1 files changed, 51 insertions, 0 deletions

diff --git a/src/test/isolation/expected/eval-plan-qual.out b/src/test/isolation/expected/eval-plan-qual.out
new file mode 100644
index 0000000000..ab778cbd7a
--- /dev/null
+++ b/src/test/isolation/expected/eval-plan-qual.out
@@ -0,0 +1,51 @@
+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