test_decoding: Protect against rare spurious test failures.

A bunch of tests missed specifying that empty transactions shouldn't be
displayed. That causes problems when e.g. autovacuum runs in an
unfortunate moment. The tests in question only run for a very short
time, making this quite unlikely.

Reported-By: Buildfarm member axolotl
Backpatch: 9.4, where logical decoding was introduced

contrib/test_decoding/expected/binary.out

@@ -7,22 +7,22 @@ SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot', 'test_d
 (1 row)
 
 -- succeeds, textual plugin, textual consumer
-SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'force-binary', '0');
+SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'force-binary', '0', 'skip-empty-xacts', '1');
  data 
 ------
 (0 rows)
 
 -- fails, binary plugin, textual consumer
-SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'force-binary', '1');
+SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'force-binary', '1', 'skip-empty-xacts', '1');
 ERROR:  logical decoding output plugin "test_decoding" produces binary output, but "pg_logical_slot_get_changes(name,pg_lsn,integer,text[])" expects textual data
 -- succeeds, textual plugin, binary consumer
-SELECT data FROM pg_logical_slot_get_binary_changes('regression_slot', NULL, NULL, 'force-binary', '0');
+SELECT data FROM pg_logical_slot_get_binary_changes('regression_slot', NULL, NULL, 'force-binary', '0', 'skip-empty-xacts', '1');
  data 
 ------
 (0 rows)
 
 -- succeeds, binary plugin, binary consumer
-SELECT data FROM pg_logical_slot_get_binary_changes('regression_slot', NULL, NULL, 'force-binary', '1');
+SELECT data FROM pg_logical_slot_get_binary_changes('regression_slot', NULL, NULL, 'force-binary', '1', 'skip-empty-xacts', '1');
  data 
 ------
 (0 rows)

contrib/test_decoding/sql/binary.sql

@@ -3,12 +3,12 @@ SET synchronous_commit = on;
 
 SELECT 'init' FROM pg_create_logical_replication_slot('regression_slot', 'test_decoding');
 -- succeeds, textual plugin, textual consumer
-SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'force-binary', '0');
+SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'force-binary', '0', 'skip-empty-xacts', '1');
 -- fails, binary plugin, textual consumer
-SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'force-binary', '1');
+SELECT data FROM pg_logical_slot_get_changes('regression_slot', NULL, NULL, 'force-binary', '1', 'skip-empty-xacts', '1');
 -- succeeds, textual plugin, binary consumer
-SELECT data FROM pg_logical_slot_get_binary_changes('regression_slot', NULL, NULL, 'force-binary', '0');
+SELECT data FROM pg_logical_slot_get_binary_changes('regression_slot', NULL, NULL, 'force-binary', '0', 'skip-empty-xacts', '1');
 -- succeeds, binary plugin, binary consumer
-SELECT data FROM pg_logical_slot_get_binary_changes('regression_slot', NULL, NULL, 'force-binary', '1');
+SELECT data FROM pg_logical_slot_get_binary_changes('regression_slot', NULL, NULL, 'force-binary', '1', 'skip-empty-xacts', '1');
 
 SELECT 'init' FROM pg_drop_replication_slot('regression_slot');