testlogship is a basic test that replication generally functions with
log shipping.  
  
It creates three simple tables as one replication set, and replicates
them from one database to another.
  
The three tables are of the three interesting types:
  
1.  table1 has a formal primary key

2.  table2 lacks a formal primary key, but has a candidate primary key

It tries replicating a third table, which has an invalid candidate
primary key (columns not defined NOT NULL), which should cause it to
be rejected.  That is done in a slonik TRY {} block.

It also creates...

3.  table4 which has columns of all sorts of vaguely esoteric types to
exercise that points, paths, bitmaps, mac addresses, and inet types
replicate properly.

It then loads data into these tables.

The test proceeds to run a DDL script which alters the schema for
table 4, adding two new columns, one to be populated via a default,
for new tuples; the other has no default, but we assign the value 42
to all tuples existing at the time that the DDL script runs.

Note that node #2 (subscriber) has slon configuration managed via
config file