function_returns() cannot find functions

[jonjonw]

function_returns() cannot seem to detect functions that has_function() can detect.

For example,

BEGIN;
SELECT plan(2);

CREATE FUNCTION _test(val int)
RETURNS VOID
LANGUAGE SQL AS $$
    SELECT 1;
$$;

SELECT has_function('_test', '{int}'::text[]);
SELECT function_returns('_test', '{int}'::text[], 'void');

SELECT * FROM finish();
ROLLBACK;

results in:

pg_prove -r bug.pg 
bug.pg .. 1/2 
# Failed test 2: "Function _test(int) should return void"
#     Function _test(int) does not exist
# Looks like you failed 1 test of 2
bug.pg .. Failed 1/2 subtests 

Test Summary Report
-------------------
bug.pg (Wstat: 0 Tests: 2 Failed: 1)
  Failed test:  2
Files=1, Tests=2,  0 wallclock secs ( 0.02 usr +  0.00 sys =  0.02 CPU)
Result: FAIL

[theory]

This is due to a limitation of the text formatting of argument data types; from the documentation for function_returns():

Tests that a particular function returns a particular data type. The :args[]
and :type arguments should be formatted as they would be displayed in the
view of a function using the \df command in psql. For example, use
"character varying" rather than "varchar", and "boolean" rather than "bool".

In your case, that means you have to use integer instead of int. Here's how it looks in psql:

david=# CREATE FUNCTION _test(val int) RETURNS VOID LANGUAGE SQL AS 'SELECT 1';
CREATE FUNCTION
Time: 7.428 ms
david=# \df _test 
                       List of functions
 Schema | Name  | Result data type | Argument data types | Type 
--------+-------+------------------+---------------------+------
 public | _test | void             | val integer         | func