-- test input and output
SELECT '1'::unit; -- unit_in
 unit 
------
 1
(1 row)

SELECT unit(1); -- dbl2unit
 unit 
------
 1
(1 row)

CREATE TEMP TABLE u (u unit);
INSERT INTO u VALUES ('1');
SELECT * FROM u;
 u 
---
 1
(1 row)

-- test constructors
SELECT meter();
 meter 
-------
 1 m
(1 row)

SELECT meter(2.0) AS two_meters;
 two_meters 
------------
 2 m
(1 row)

SELECT kilogram();
 kilogram 
----------
 1 kg
(1 row)

SELECT kilogram(3.0) AS three_kilogram;
 three_kilogram 
----------------
 3 kg
(1 row)

SELECT second();
 second 
--------
 1 s
(1 row)

SELECT second(4.0) AS four_seconds;
 four_seconds 
--------------
 4 s
(1 row)

SELECT ampere();
 ampere 
--------
 1 A
(1 row)

SELECT ampere(5.0) AS five_ampere;
 five_ampere 
-------------
 5 A
(1 row)

SELECT kelvin();
 kelvin 
--------
 1 K
(1 row)

SELECT kelvin(6.0) AS six_kelvin;
 six_kelvin 
------------
 6 K
(1 row)

SELECT mole();
 mole  
-------
 1 mol
(1 row)

SELECT mole(7.0) AS seven_mole;
 seven_mole 
------------
 7 mol
(1 row)

SELECT candela();
 candela 
---------
 1 cd
(1 row)

SELECT candela(8.0) AS eight_candela;
 eight_candela 
---------------
 8 cd
(1 row)

SELECT byte();
 byte 
------
 1 B
(1 row)

SELECT byte(9.0) AS nine_byte;
 nine_byte 
-----------
 9 B
(1 row)

-- test dimensionless scales
SELECT unit(0) AS zero, unit(1e-6) AS "1e-6", unit(0.001) AS "0.001", unit(1.0) AS "1", unit(1000.0) AS "1000";
 zero | 1e-6  | 0.001 | 1 | 1000 
------+-------+-------+---+------
 0    | 1e-06 | 0.001 | 1 | 1000
(1 row)

-- test SI prefixes
SELECT meter(0) AS zero, meter(1e-6) AS "µm", meter(0.001) AS mm, meter(1.0) AS m, meter(1000.0) AS km;
 zero |  µm  |  mm  |  m  |  km  
------+------+------+-----+------
 0 m  | 1 µm | 1 mm | 1 m | 1 km
(1 row)

SELECT kilogram(0) AS zero, kilogram(1e-6) AS mg, kilogram(0.001) AS g, kilogram(1.0) AS kg, kilogram(1000.0) AS "Mg";
 zero |  mg  |  g  |  kg  |  Mg  
------+------+-----+------+------
 0 kg | 1 mg | 1 g | 1 kg | 1 Mg
(1 row)

-- test combined units (exactly one unit with exponent 1 in numerator)
SELECT meter(0)/second() AS zero, meter(1e-6)/second() AS "µm", meter(0.001)/second() AS mm, meter(1.0)/second() AS m, meter(1000.0)/second() AS km;
 zero  |   µm   |   mm   |   m   |   km   
-------+--------+--------+-------+--------
 0 m/s | 1 µm/s | 1 mm/s | 1 m/s | 1 km/s
(1 row)

SELECT kilogram(0)/second() AS zero, kilogram(1e-6)/second() AS mg, kilogram(0.001)/second() AS g, kilogram(1.0)/second() AS kg, kilogram(1000.0)/second() AS "Mg";
  zero  |   mg   |   g   |   kg   |   Mg   
--------+--------+-------+--------+--------
 0 kg/s | 1 mg/s | 1 g/s | 1 kg/s | 1 Mg/s
(1 row)

-- test parser
SELECT '1 m'::unit;
 unit 
------
 1 m
(1 row)

SELECT '-1 m/s'::unit;
  unit  
--------
 -1 m/s
(1 row)

SELECT '10 dm^3'::unit, '10l'::unit;
   unit   |   unit   
----------+----------
 0.01 m^3 | 0.01 m^3
(1 row)

SELECT '9.81 kg*m/s^2'::unit, '9.81 kg*m/s*s'::unit, '9.81 kg*m/s/s'::unit;
  unit  |  unit  |  unit  
--------+--------+--------
 9.81 N | 9.81 N | 9.81 N
(1 row)

SELECT '1 foobar'::unit AS error;
ERROR:  unit "foobar" is not known
LINE 1: SELECT '1 foobar'::unit AS error;
               ^
-- special values
SELECT '-0'::unit, -'0'::unit, '-0 m'::unit, -'0 m'::unit;
 unit | ?column? | unit | ?column? 
------+----------+------+----------
 -0   | -0       | -0 m | -0 m
(1 row)

SELECT 'infinity'::unit, 'Infinity m'::unit, 'inf A'::unit;
   unit   |    unit    |    unit    
----------+------------+------------
 Infinity | Infinity m | Infinity A
(1 row)

SELECT '-infinity'::unit, '-Infinity m'::unit, 'Inf A'::unit;
   unit    |    unit     |    unit    
-----------+-------------+------------
 -Infinity | -Infinity m | Infinity A
(1 row)

SELECT 'nan'::unit, 'NaN'::unit;
 unit | unit 
------+------
 NaN  | NaN
(1 row)

-- test parser arithmetic
SELECT '1|10'::unit, '1|10 m'::unit;
 unit |  unit  
------+--------
 0.1  | 100 mm
(1 row)

SELECT '2 m + 3 m - 4 m'::unit, '6 m - 3 m - 2 m'::unit, '6 m - 3 m + 1 m'::unit;
 unit | unit | unit 
------+------+------
 1 m  | 1 m  | 4 m
(1 row)

SELECT '2 m * 3 m'::unit, '2 m / 3 m'::unit, '10 m / 5 m / 2 m'::unit;
 unit  |       unit        |  unit  
-------+-------------------+--------
 6 m^2 | 0.666666666666667 | 1 m^-1
(1 row)

SELECT '2 m^2 + 3 m * 4 m'::unit, '2 m * 3 m / 4 m * 5 m'::unit;
  unit  | unit 
--------+------
 14 m^2 | 0.3
(1 row)

SELECT '2 m * (1 m + 3 m)'::unit;
 unit  
-------
 8 m^2
(1 row)

SELECT '- m'::unit, '/ m'::unit;
 unit |  unit  
------+--------
 -1 m | 1 m^-1
(1 row)

SELECT '4+5'::unit, '4-5'::unit, '4(-5)'::unit, '4*5'::unit, '4/5'::unit;
 unit | unit | unit | unit | unit 
------+------+------+------+------
 9    | -1   | -20  | 20   | 0.8
(1 row)

-- problematic cases
SELECT '1 cd'::unit AS candela; -- candela vs centiday
 candela 
---------
 1 cd
(1 row)

SELECT '1 Pa'::unit AS pascal; -- pascal vs petayear
 pascal 
--------
 1 Pa
(1 row)

SELECT '1 yg'::unit AS yoctogram, '1.00001 yg'::unit AS actual_yoctogram; -- "yg" had rounding problems in the past
 yoctogram | actual_yoctogram 
-----------+------------------
 1 yg      | 1.00001 yg
(1 row)

SELECT '1 min'::unit AS minute; -- minute vs milliinch
   minute   
------------
 00:01:00 s
(1 row)

SELECT '1 ft'::unit AS foot; -- foot vs femtotonne
   foot   
----------
 304.8 mm
(1 row)

SELECT '1 yd'::unit AS yard; -- yard vs yoctoday
   yard   
----------
 914.4 mm
(1 row)

-- units whose definition changed between v2 and 3
SELECT 'a'::unit AS are;
   are   
---------
 100 m^2
(1 row)

SELECT 'da'::unit AS day;
 day 
-----
 1 d
(1 row)

SELECT 'rad'::unit AS radiation;
 radiation 
-----------
 10 mGy
(1 row)

-- check which prefix/unit combinations produce other dimensions (parser conflicts)
SELECT
  p, u, (p||u)::unit
FROM
  prefixes CROSS JOIN units
WHERE
  u <> 'kg' AND
  dimension(u::unit) != dimension((p||u)::unit) AND
  p||u NOT IN ('dat') -- skip ambiguous unit
ORDER BY lower(p) COLLATE "C", lower(u) COLLATE "C";
 p |  u  |             unit              
---+-----+-------------------------------
 a | t   | 98.0665 kPa
 c | d   | 1 cd
 d | a   | 1 d
 f | t   | 304.8 mm
 G | s   | 100 µT
 h | bar | 1.05457181764616e-34 m^2*kg/s
 h | d   | 0.238480942392 m^3
 k | in  | 600 g
 m | in  | 00:01:00 s
 n | t   | 1 N
 P | a   | 1 Pa
 p | a   | 1 Pa
 p | in  | 0.020457405 m^3
 p | t   | 0.000473176473 m^3
 q | t   | 0.000946352946 m^3
 r | d   | 5.0292 m
 y | d   | 914.4 mm
(17 rows)