Split the plpython regression test into test cases arranged by topic, instead

of the previous monolithic setup-create-run sequence, that was apparently
inherited from a previous test infrastructure, but makes working with the
tests and adding new ones weird.

src/pl/plpython/sql/plpython_setof.sql

@@ -0,0 +1,46 @@
+--
+-- Test returning SETOF
+--
+
+CREATE FUNCTION test_setof_as_list(count integer, content text) RETURNS SETOF text AS $$
+return [ content ]*count
+$$ LANGUAGE plpythonu;
+
+CREATE FUNCTION test_setof_as_tuple(count integer, content text) RETURNS SETOF text AS $$
+t = ()
+for i in xrange(count):
+	t += ( content, )
+return t
+$$ LANGUAGE plpythonu;
+
+CREATE FUNCTION test_setof_as_iterator(count integer, content text) RETURNS SETOF text AS $$
+class producer:
+	def __init__ (self, icount, icontent):
+		self.icontent = icontent
+		self.icount = icount
+	def __iter__ (self):
+		return self
+	def next (self):
+		if self.icount == 0:
+			raise StopIteration
+		self.icount -= 1
+		return self.icontent
+return producer(count, content)
+$$ LANGUAGE plpythonu;
+
+
+-- Test set returning functions
+SELECT test_setof_as_list(0, 'list');
+SELECT test_setof_as_list(1, 'list');
+SELECT test_setof_as_list(2, 'list');
+SELECT test_setof_as_list(2, null);
+
+SELECT test_setof_as_tuple(0, 'tuple');
+SELECT test_setof_as_tuple(1, 'tuple');
+SELECT test_setof_as_tuple(2, 'tuple');
+SELECT test_setof_as_tuple(2, null);
+
+SELECT test_setof_as_iterator(0, 'list');
+SELECT test_setof_as_iterator(1, 'list');
+SELECT test_setof_as_iterator(2, 'list');
+SELECT test_setof_as_iterator(2, null);