fix(ore): return null when comparing null ore values

sql/000-ore.sql

@@ -239,13 +239,24 @@ RETURNS integer AS $$
   DECLARE
     cmp_result integer;
   BEGIN
-    IF (array_length(a, 1) = 0 OR a IS NULL) AND (array_length(b, 1) = 0 OR b IS NULL) THEN
+
+    -- NULLs are NULL
+    IF a IS NULL OR b IS NULL THEN
+      RETURN NULL;
+    END IF;
+
+    -- empty a and b
+    IF cardinality(a) = 0 AND cardinality(b) = 0 THEN
       RETURN 0;
     END IF;
-    IF array_length(a, 1) = 0 OR a IS NULL THEN
+
+    -- empty a and some b
+    IF (cardinality(a) = 0) AND cardinality(b) > 0 THEN
       RETURN -1;
     END IF;
-    IF array_length(b, 1) = 0 OR a IS NULL THEN
+
+    -- some a and empty b
+    IF cardinality(a) > 0 AND (cardinality(b) = 0) THEN
       RETURN 1;
     END IF;
 

tests/operators-ore.sql

@@ -12,8 +12,7 @@ CREATE TABLE users
 
 TRUNCATE TABLE users;
 
-
-TRUNCATE TABLE users;
+INSERT INTO users (name_encrypted) VALUES (NULL);
 
 -- User with "LOW" value
 INSERT INTO users (name_encrypted) VALUES (
@@ -57,6 +56,9 @@ DO $$
     -- SANITY CHECK
     ASSERT (SELECT EXISTS (SELECT id FROM users WHERE cs_ore_64_8_v1(name_encrypted) < cs_ore_64_8_v1(ore_json)));
 
+    -- NULL VALUES SHOULD BE IGNORED
+    ASSERT (SELECT (SELECT COUNT(*) FROM (SELECT id FROM users WHERE cs_ore_64_8_v1(name_encrypted) < cs_ore_64_8_v1(ore_json)) as count) = 1);
+
     ASSERT (SELECT EXISTS (
       SELECT id FROM users WHERE name_encrypted < ore_cs_encrypted::jsonb
     ));