Verify that typemaps are applied to stream_each_tuple

This currently fails.

spec/pg/result_spec.rb

@@ -86,6 +86,8 @@
 	end
 
 	context "result streaming in single row mode" do
+		let!(:textdec_int){ PG::TextDecoder::Integer.new name: 'INT4', oid: 23 }
+
 		it "can iterate over all rows as Hash" do
 			@conn.send_query( "SELECT generate_series(2,4) AS a; SELECT 1 AS b, generate_series(5,6) AS c" )
 			@conn.set_single_row_mode
@@ -145,13 +147,14 @@
 			expect( @conn.get_result ).to be_nil
 		end
 
-		it "can iterate over all rows as PG::Tuple with symbols" do
+		it "can iterate over all rows as PG::Tuple with symbols and typemap" do
 			@conn.send_query( "SELECT generate_series(2,4) AS a" )
 			@conn.set_single_row_mode
 			res = @conn.get_result.field_names_as(:symbol)
+			res.type_map = PG::TypeMapByColumn.new [textdec_int]
 			tuples = res.stream_each_tuple.to_a
-			expect( tuples[0][0] ).to eq( "2" )
-			expect( tuples[1][:a] ).to eq( "3" )
+			expect( tuples[0][0] ).to eq( 2 )
+			expect( tuples[1][:a] ).to eq( 3 )
 			expect( @conn.get_result ).to be_nil
 		end