diff --git a/src/test/modules/test_bitmapset/expected/test_bitmapset.out b/src/test/modules/test_bitmapset/expected/test_bitmapset.out
index be7b6399c82..8ad7cb71330 100644
--- a/src/test/modules/test_bitmapset/expected/test_bitmapset.out
+++ b/src/test/modules/test_bitmapset/expected/test_bitmapset.out
@@ -59,13 +59,6 @@ SELECT test_bms_add_member('(b 10)', 10) AS result;
  (b 10)
 (1 row)
 
--- Test module check
-SELECT test_bms_add_member('(b)', NULL) AS result;
- result 
---------
- 
-(1 row)
-
 -- bms_replace_members()
 SELECT test_bms_replace_members(NULL, '(b 1 2 3)') AS result;
   result   
@@ -76,7 +69,7 @@ SELECT test_bms_replace_members(NULL, '(b 1 2 3)') AS result;
 SELECT test_bms_replace_members('(b 1 2 3)', NULL) AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 SELECT test_bms_replace_members('(b 1 2 3)', '(b 3 5 6)') AS result;
@@ -104,19 +97,20 @@ SELECT test_bms_replace_members('(b 1 2 3 4 5)', '(b 500 600)') AS result;
  (b 500 600)
 (1 row)
 
--- Test module checks
+-- Replace with an empty set
 SELECT test_bms_replace_members('(b 1 2 3)', NULL) AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 SELECT test_bms_replace_members('(b 5)', NULL) AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
+-- Replace empty set with another set
 SELECT test_bms_replace_members(NULL, '(b 5)') AS result;
  result 
 --------
@@ -126,7 +120,7 @@ SELECT test_bms_replace_members(NULL, '(b 5)') AS result;
 SELECT test_bms_replace_members(NULL, NULL) AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 -- bms_del_member()
@@ -135,13 +129,13 @@ ERROR:  negative bitmapset member not allowed
 SELECT test_bms_del_member('(b)', 10) AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 SELECT test_bms_del_member('(b 10)', 10) AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 SELECT test_bms_del_member('(b 10)', 5) AS result;
@@ -189,30 +183,24 @@ SELECT test_bms_del_member('(b 1 50 100 200)', 100) AS result;
  (b 1 50 200)
 (1 row)
 
--- Test module checks
+-- Empty resulting set
 SELECT test_bms_del_member('(b 42)', 42) AS result;
  result 
 --------
- 
-(1 row)
-
-SELECT test_bms_del_member('(b 5)', NULL) AS result;
- result 
---------
- 
+ <>
 (1 row)
 
 -- bms_del_members()
 SELECT test_bms_del_members('(b)', '(b 10)') AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 SELECT test_bms_del_members('(b 10)', '(b 10)') AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 SELECT test_bms_del_members('(b 10)', '(b 5)') AS result;
@@ -252,7 +240,7 @@ SELECT test_bms_del_members('(b 1 2 100 200 300)', '(b 200 300)') AS result;
  (b 1 2 100)
 (1 row)
 
--- Test module checks
+-- Test with empty sets
 SELECT test_bms_del_members('(b 5)', NULL) AS result;
  result 
 --------
@@ -262,7 +250,7 @@ SELECT test_bms_del_members('(b 5)', NULL) AS result;
 SELECT test_bms_del_members(NULL, '(b 5)') AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 -- bms_join()
@@ -303,23 +291,11 @@ SELECT test_bms_join('(b 1 2)', '(b 100 200 300)') AS result;
  (b 1 2 100 200 300)
 (1 row)
 
--- Test module checks
-SELECT test_bms_join('(b 5)', NULL) AS result;
- result 
---------
- (b 5)
-(1 row)
-
-SELECT test_bms_join(NULL, '(b 5)') AS result;
- result 
---------
- (b 5)
-(1 row)
-
+-- Both sets empty
 SELECT test_bms_join(NULL, NULL) AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 -- bms_union()
@@ -330,18 +306,18 @@ SELECT test_bms_union('(b 1 3 5)', '(b 3 5 7)') AS result;
  (b 1 3 5 7)
 (1 row)
 
--- Union with NULL
+-- Union with empty set
 SELECT test_bms_union('(b 1 3 5)', '(b)') AS result;
   result   
 -----------
  (b 1 3 5)
 (1 row)
 
--- Union of empty with empty
+-- Try both sets empty
 SELECT test_bms_union('(b)', '(b)') AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 -- Overlapping ranges
@@ -354,7 +330,7 @@ SELECT test_bms_union(
  (b 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20)
 (1 row)
 
--- Union with varrying word counts
+-- Union with varying word counts
 SELECT test_bms_union('(b 1 2)', '(b 100 300)') AS result;
      result      
 -----------------
@@ -367,7 +343,7 @@ SELECT test_bms_union('(b 100 300)', '(b 1 2)') AS result;
  (b 1 2 100 300)
 (1 row)
 
--- Test module checks
+-- Unions to empty sets
 SELECT test_bms_union('(b 5)', NULL) AS result;
  result 
 --------
@@ -383,7 +359,7 @@ SELECT test_bms_union(NULL, '(b 5)') AS result;
 SELECT test_bms_union(NULL, NULL) AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 -- bms_intersect()
@@ -398,17 +374,17 @@ SELECT test_bms_intersect('(b 1 3 5)', '(b 3 5 7)') AS result;
 SELECT test_bms_intersect('(b 1 3 5)', '(b 2 4 6)') AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 -- Intersect with empty
 SELECT test_bms_intersect('(b 1 3 5)', '(b)') AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
--- Intersect with varrying word counts
+-- Intersect with varying word counts
 SELECT test_bms_intersect('(b 1 300)', '(b 1 2 3 4 5)') AS result;
  result 
 --------
@@ -421,29 +397,23 @@ SELECT test_bms_intersect('(b 1 2 3 4 5)', '(b 1 300)') AS result;
  (b 1)
 (1 row)
 
--- Test module checks
-SELECT test_bms_intersect('(b 1)', '(b 2)') AS result;
- result 
---------
- 
-(1 row)
-
+-- Intersect with empty sets
 SELECT test_bms_intersect('(b 5)', NULL) AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 SELECT test_bms_intersect(NULL, '(b 5)') AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 SELECT test_bms_intersect(NULL, NULL) AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 -- bms_int_members()
@@ -458,14 +428,14 @@ SELECT test_bms_int_members('(b 1 3 5)', '(b 3 5 7)') AS result;
 SELECT test_bms_int_members('(b 1 3 5)', '(b 2 4 6)') AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 -- Intersect with empty
 SELECT test_bms_int_members('(b 1 3 5)', '(b)') AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 -- Multiple members
@@ -475,29 +445,23 @@ SELECT test_bms_int_members('(b 0 31 32 63 64)', '(b 31 32 64 65)') AS result;
  (b 31 32 64)
 (1 row)
 
--- Test module checks
-SELECT test_bms_int_members('(b 1)', '(b 2)') AS result;
- result 
---------
- 
-(1 row)
-
+-- Intersect with empty sets
 SELECT test_bms_int_members('(b 5)', NULL) AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 SELECT test_bms_int_members(NULL, '(b 5)') AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 SELECT test_bms_int_members(NULL, NULL) AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 -- bms_difference()
@@ -519,14 +483,14 @@ SELECT test_bms_difference('(b 1 3 5)', '(b 2 4 6)') AS result;
 SELECT test_bms_difference('(b 1 3 5)', '(b 1 3 5)') AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 -- Substraction to empty
 SELECT test_bms_difference('(b 42)', '(b 42)') AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 -- Subtraction edge case
@@ -556,7 +520,7 @@ SELECT test_bms_difference('(b 1 2 100 200)', '(b 1 2)') AS result;
 SELECT test_bms_difference('(b 5)', '(b 5 10)') AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 SELECT test_bms_difference('(b 5)', NULL) AS result;
@@ -568,13 +532,13 @@ SELECT test_bms_difference('(b 5)', NULL) AS result;
 SELECT test_bms_difference(NULL, '(b 5)') AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 SELECT test_bms_difference(NULL, NULL) AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 -- bms_is_member()
@@ -604,13 +568,6 @@ SELECT test_bms_is_member('(b)', 1) AS result;
  f
 (1 row)
 
--- Test module check
-SELECT test_bms_is_member('(b 5)', NULL) AS result;
- result 
---------
- f
-(1 row)
-
 -- bms_member_index()
 SELECT test_bms_member_index(NULL, 1) AS result;
  result 
@@ -655,19 +612,6 @@ SELECT test_bms_member_index('(b 1 50 100 200)', 200) AS result;
       3
 (1 row)
 
--- Test module checks
-SELECT test_bms_member_index('', 5) AS result;
- result 
---------
-     -1
-(1 row)
-
-SELECT test_bms_member_index(NULL, 5) AS result;
- result 
---------
-     -1
-(1 row)
-
 -- bms_num_members()
 SELECT test_bms_num_members('(b)') AS result;
  result 
@@ -694,6 +638,12 @@ SELECT test_bms_equal('(b)', '(b)') AS result;
  t
 (1 row)
 
+SELECT test_bms_equal(NULL, NULL) AS result;
+ result 
+--------
+ t
+(1 row)
+
 SELECT test_bms_equal('(b)', '(b 1 3 5)') AS result;
  result 
 --------
@@ -731,25 +681,6 @@ SELECT test_bms_equal('(b 5 10)', '(b 100 200 300)') AS result;
  f
 (1 row)
 
--- Test module checks
-SELECT test_bms_equal('(b 5)', NULL) AS result;
- result 
---------
- f
-(1 row)
-
-SELECT test_bms_equal(NULL, '(b 5)') AS result;
- result 
---------
- f
-(1 row)
-
-SELECT test_bms_equal(NULL, NULL) AS result;
- result 
---------
- t
-(1 row)
-
 -- bms_compare()
 SELECT test_bms_compare('(b)', '(b)') AS result;
  result 
@@ -796,25 +727,6 @@ SELECT test_bms_compare(
      -1
 (1 row)
 
--- Test module checks
-SELECT test_bms_compare('(b 5)', NULL) AS result;
- result 
---------
-      1
-(1 row)
-
-SELECT test_bms_compare(NULL, '(b 5)') AS result;
- result 
---------
-     -1
-(1 row)
-
-SELECT test_bms_compare(NULL, NULL) AS result;
- result 
---------
-      0
-(1 row)
-
 -- bms_add_range()
 SELECT test_bms_add_range('(b)', -5, 10); -- error
 ERROR:  negative bitmapset member not allowed
@@ -883,43 +795,6 @@ SELECT length(test_bms_add_range('(b 1 2)', 200, 250)) AS result;
     211
 (1 row)
 
--- Test module checks
-SELECT test_bms_add_range('(b 5)', 5, NULL) AS result;
- result 
---------
- 
-(1 row)
-
-SELECT test_bms_add_range('(b 5)', NULL, 10) AS result;
- result 
---------
- 
-(1 row)
-
-SELECT test_bms_add_range('(b 5)', NULL, NULL) AS result;
- result 
---------
- 
-(1 row)
-
-SELECT test_bms_add_range(NULL, 5, 10) AS result;
-      result      
-------------------
- (b 5 6 7 8 9 10)
-(1 row)
-
-SELECT test_bms_add_range(NULL, 10, 5) AS result;
- result 
---------
- 
-(1 row)
-
-SELECT test_bms_add_range(NULL, NULL, NULL) AS result;
- result 
---------
- 
-(1 row)
-
 -- bms_membership()
 SELECT test_bms_membership('(b)') AS result;
  result 
@@ -965,17 +840,10 @@ SELECT test_bms_is_empty('(b 1)') AS result;
  f
 (1 row)
 
--- Test module check
-SELECT test_bms_is_empty(NULL) AS result;
- result 
---------
- t
-(1 row)
-
 -- bms_singleton_member()
-SELECT test_bms_singleton_member('(b)'); -- error
+SELECT test_bms_singleton_member('(b)'); -- error empty set
 ERROR:  bitmapset is empty
-SELECT test_bms_singleton_member('(b 1 2)'); -- error
+SELECT test_bms_singleton_member('(b 1 2)'); -- error multiple members
 ERROR:  bitmapset has multiple members
 SELECT test_bms_singleton_member('(b 42)') AS result;
  result 
@@ -983,45 +851,26 @@ SELECT test_bms_singleton_member('(b 42)') AS result;
      42
 (1 row)
 
--- Test module check
-SELECT test_bms_singleton_member(NULL) AS result;
- result 
---------
-       
-(1 row)
-
 -- bms_get_singleton_member()
-SELECT test_bms_get_singleton_member('(b)', 1000);
- test_bms_get_singleton_member 
--------------------------------
-                          1000
-(1 row)
-
--- Not a singleton, returns input default
-SELECT test_bms_get_singleton_member('(b 3 6)', 1000) AS result;
- result 
---------
-   1000
-(1 row)
-
--- Singletone, returns sole member
-SELECT test_bms_get_singleton_member('(b 400)', 1000) AS result;
+-- Try with an empty set
+SELECT test_bms_get_singleton_member(NULL) AS result;
  result 
 --------
-    400
+     -1
 (1 row)
 
--- Test module checks
-SELECT test_bms_get_singleton_member('', 1000) AS result;
+-- Not a singleton, returns -1
+SELECT test_bms_get_singleton_member('(b 3 6)') AS result;
  result 
 --------
-   1000
+     -1
 (1 row)
 
-SELECT test_bms_get_singleton_member(NULL, -1) AS result;
+-- Singleton, returns sole member
+SELECT test_bms_get_singleton_member('(b 400)') AS result;
  result 
 --------
-     -1
+    400
 (1 row)
 
 -- bms_next_member() and bms_prev_member()
@@ -1088,49 +937,6 @@ SELECT test_bms_prev_member('(b 0 63 64 127)', -1) AS result;
     127
 (1 row)
 
--- Test module checks
-SELECT test_bms_next_member('', 5) AS result;
- result 
---------
-     -2
-(1 row)
-
-SELECT test_bms_next_member('(b 5)', NULL) AS result;
- result 
---------
-     -2
-(1 row)
-
-SELECT test_bms_next_member(NULL, 5) AS result;
- result 
---------
-     -2
-(1 row)
-
-SELECT test_bms_next_member(NULL, NULL) AS result;
- result 
---------
-     -2
-(1 row)
-
-SELECT test_bms_prev_member('', 5) AS result;
- result 
---------
-     -2
-(1 row)
-
-SELECT test_bms_prev_member('(b 5)', NULL) AS result;
- result 
---------
-     -2
-(1 row)
-
-SELECT test_bms_prev_member(NULL, 5) AS result;
- result 
---------
-     -2
-(1 row)
-
 -- bms_hash_value()
 SELECT test_bms_hash_value('(b)') = 0 AS result;
  result 
@@ -1176,25 +982,6 @@ SELECT test_bms_overlap('(b)', '(b 1 3 5)') AS result;
  f
 (1 row)
 
--- Test module checks
-SELECT test_bms_overlap('(b 5)', NULL) AS result;
- result 
---------
- f
-(1 row)
-
-SELECT test_bms_overlap(NULL, '(b 5)') AS result;
- result 
---------
- f
-(1 row)
-
-SELECT test_bms_overlap(NULL, NULL) AS result;
- result 
---------
- f
-(1 row)
-
 -- bms_is_subset()
 SELECT test_bms_is_subset('(b)', '(b 1 3 5)') AS result;
  result 
@@ -1398,30 +1185,11 @@ SELECT test_bms_subset_compare('(b 2 64 128)', '(b 1 65)') AS result;
       3
 (1 row)
 
--- Test module checks
-SELECT test_bms_subset_compare('(b 5)', NULL) AS result;
- result 
---------
-      2
-(1 row)
-
-SELECT test_bms_subset_compare(NULL, '(b 5)') AS result;
- result 
---------
-      1
-(1 row)
-
-SELECT test_bms_subset_compare(NULL, NULL) AS result;
- result 
---------
-      0
-(1 row)
-
 -- bms_copy()
 SELECT test_bms_copy(NULL) AS result;
  result 
 --------
- 
+ <>
 (1 row)
 
 SELECT test_bms_copy('(b 1 3 5 7)') AS result;
@@ -1430,13 +1198,6 @@ SELECT test_bms_copy('(b 1 3 5 7)') AS result;
  (b 1 3 5 7)
 (1 row)
 
--- Test module check
-SELECT test_bms_copy(NULL) AS result;
- result 
---------
- 
-(1 row)
-
 -- bms_add_members()
 SELECT test_bms_add_members('(b 1 3)', '(b 5 7)') AS result;
    result    
@@ -1481,13 +1242,6 @@ SELECT test_bitmap_hash('(b 1 3 5)') != test_bitmap_hash('(b 2 4 6)') AS result;
  t
 (1 row)
 
--- Test module check
-SELECT test_bitmap_hash(NULL) AS result;
- result 
---------
-      0
-(1 row)
-
 -- bitmap_match()
 SELECT test_bitmap_match('(b)', '(b)') AS result;
  result 
@@ -1547,25 +1301,6 @@ SELECT (test_bitmap_match('(b)', '(b)') = 0) =
  t
 (1 row)
 
--- Test module checks
-SELECT test_bitmap_match('(b 5)', NULL) AS result;
- result 
---------
-      1
-(1 row)
-
-SELECT test_bitmap_match(NULL, '(b 5)') AS result;
- result 
---------
-      1
-(1 row)
-
-SELECT test_bitmap_match(NULL, NULL) AS result;
- result 
---------
-      0
-(1 row)
-
 -- bms_overlap_list()
 SELECT test_bms_overlap_list('(b 0)', ARRAY[0]) AS result;
  result 
@@ -1678,25 +1413,6 @@ SELECT test_bms_nonempty_difference('(b 1 2)', '(b 50 100)') AS result;
  t
 (1 row)
 
--- Test module checks
-SELECT test_bms_nonempty_difference('(b 5)', NULL) AS result;
- result 
---------
- t
-(1 row)
-
-SELECT test_bms_nonempty_difference(NULL, '(b 5)') AS result;
- result 
---------
- f
-(1 row)
-
-SELECT test_bms_nonempty_difference(NULL, NULL) AS result;
- result 
---------
- f
-(1 row)
-
 -- random operations
 SELECT test_random_operations(-1, 10000, 81920, 0) > 0 AS result;
  result 
diff --git a/src/test/modules/test_bitmapset/sql/test_bitmapset.sql b/src/test/modules/test_bitmapset/sql/test_bitmapset.sql
index c6e6bce60a3..18313dfa350 100644
--- a/src/test/modules/test_bitmapset/sql/test_bitmapset.sql
+++ b/src/test/modules/test_bitmapset/sql/test_bitmapset.sql
@@ -18,8 +18,6 @@ SELECT test_bms_add_member('(b 5)', 10) AS result;
 SELECT test_bms_add_member('(b 10)', 5) AS result;
 -- idempotent change
 SELECT test_bms_add_member('(b 10)', 10) AS result;
--- Test module check
-SELECT test_bms_add_member('(b)', NULL) AS result;
 
 -- bms_replace_members()
 SELECT test_bms_replace_members(NULL, '(b 1 2 3)') AS result;
@@ -29,9 +27,10 @@ SELECT test_bms_replace_members('(b 1 2 3)', '(b 3 5)') AS result;
 SELECT test_bms_replace_members('(b 1 2)', '(b 3 5 7)') AS result;
 -- Force repalloc() with larger set
 SELECT test_bms_replace_members('(b 1 2 3 4 5)', '(b 500 600)') AS result;
--- Test module checks
+-- Replace with an empty set
 SELECT test_bms_replace_members('(b 1 2 3)', NULL) AS result;
 SELECT test_bms_replace_members('(b 5)', NULL) AS result;
+-- Replace empty set with another set
 SELECT test_bms_replace_members(NULL, '(b 5)') AS result;
 SELECT test_bms_replace_members(NULL, NULL) AS result;
 
@@ -49,9 +48,8 @@ SELECT test_bms_del_member(test_bms_add_range('(b)', 30, 34), 32) AS result;
 SELECT test_bms_del_member('(b 1 200)', 200) AS result;
 SELECT test_bms_del_member('(b 1 50 100 200)', 200) AS result;
 SELECT test_bms_del_member('(b 1 50 100 200)', 100) AS result;
--- Test module checks
+-- Empty resulting set
 SELECT test_bms_del_member('(b 42)', 42) AS result;
-SELECT test_bms_del_member('(b 5)', NULL) AS result;
 
 -- bms_del_members()
 SELECT test_bms_del_members('(b)', '(b 10)') AS result;
@@ -63,7 +61,7 @@ SELECT test_bms_del_members('(b 5 100 200)', '(b 200)') AS result;
 -- Force word count changes
 SELECT test_bms_del_members('(b 1 2 100 200 300)', '(b 1 2)') AS result;
 SELECT test_bms_del_members('(b 1 2 100 200 300)', '(b 200 300)') AS result;
--- Test module checks
+-- Test with empty sets
 SELECT test_bms_del_members('(b 5)', NULL) AS result;
 SELECT test_bms_del_members(NULL, '(b 5)') AS result;
 
@@ -75,27 +73,25 @@ SELECT test_bms_join('(b 1 3 5)', '(b 1 4 5)') AS result;
 -- Force word count changes
 SELECT test_bms_join('(b 5)', '(b 100)') AS result;
 SELECT test_bms_join('(b 1 2)', '(b 100 200 300)') AS result;
--- Test module checks
-SELECT test_bms_join('(b 5)', NULL) AS result;
-SELECT test_bms_join(NULL, '(b 5)') AS result;
+-- Both sets empty
 SELECT test_bms_join(NULL, NULL) AS result;
 
 -- bms_union()
 -- Overlapping sets
 SELECT test_bms_union('(b 1 3 5)', '(b 3 5 7)') AS result;
--- Union with NULL
+-- Union with empty set
 SELECT test_bms_union('(b 1 3 5)', '(b)') AS result;
--- Union of empty with empty
+-- Try both sets empty
 SELECT test_bms_union('(b)', '(b)') AS result;
 -- Overlapping ranges
 SELECT test_bms_union(
          test_bms_add_range('(b)', 0, 15),
          test_bms_add_range('(b)', 10, 20)
        ) AS result;
--- Union with varrying word counts
+-- Union with varying word counts
 SELECT test_bms_union('(b 1 2)', '(b 100 300)') AS result;
 SELECT test_bms_union('(b 100 300)', '(b 1 2)') AS result;
--- Test module checks
+-- Unions to empty sets
 SELECT test_bms_union('(b 5)', NULL) AS result;
 SELECT test_bms_union(NULL, '(b 5)') AS result;
 SELECT test_bms_union(NULL, NULL) AS result;
@@ -107,11 +103,10 @@ SELECT test_bms_intersect('(b 1 3 5)', '(b 3 5 7)') AS result;
 SELECT test_bms_intersect('(b 1 3 5)', '(b 2 4 6)') AS result;
 -- Intersect with empty
 SELECT test_bms_intersect('(b 1 3 5)', '(b)') AS result;
--- Intersect with varrying word counts
+-- Intersect with varying word counts
 SELECT test_bms_intersect('(b 1 300)', '(b 1 2 3 4 5)') AS result;
 SELECT test_bms_intersect('(b 1 2 3 4 5)', '(b 1 300)') AS result;
--- Test module checks
-SELECT test_bms_intersect('(b 1)', '(b 2)') AS result;
+-- Intersect with empty sets
 SELECT test_bms_intersect('(b 5)', NULL) AS result;
 SELECT test_bms_intersect(NULL, '(b 5)') AS result;
 SELECT test_bms_intersect(NULL, NULL) AS result;
@@ -125,8 +120,7 @@ SELECT test_bms_int_members('(b 1 3 5)', '(b 2 4 6)') AS result;
 SELECT test_bms_int_members('(b 1 3 5)', '(b)') AS result;
 -- Multiple members
 SELECT test_bms_int_members('(b 0 31 32 63 64)', '(b 31 32 64 65)') AS result;
--- Test module checks
-SELECT test_bms_int_members('(b 1)', '(b 2)') AS result;
+-- Intersect with empty sets
 SELECT test_bms_int_members('(b 5)', NULL) AS result;
 SELECT test_bms_int_members(NULL, '(b 5)') AS result;
 SELECT test_bms_int_members(NULL, NULL) AS result;
@@ -160,8 +154,6 @@ SELECT test_bms_is_member('(b 1 3 5)', 1) AS result;
 SELECT test_bms_is_member('(b 1 3 5)', 2) AS result;
 SELECT test_bms_is_member('(b 1 3 5)', 3) AS result;
 SELECT test_bms_is_member('(b)', 1) AS result;
--- Test module check
-SELECT test_bms_is_member('(b 5)', NULL) AS result;
 
 -- bms_member_index()
 SELECT test_bms_member_index(NULL, 1) AS result;
@@ -172,9 +164,6 @@ SELECT test_bms_member_index('(b 1 3 5)', 3) AS result;
 SELECT test_bms_member_index('(b 100 200)', 100) AS result;
 SELECT test_bms_member_index('(b 100 200)', 200) AS result;
 SELECT test_bms_member_index('(b 1 50 100 200)', 200) AS result;
--- Test module checks
-SELECT test_bms_member_index('', 5) AS result;
-SELECT test_bms_member_index(NULL, 5) AS result;
 
 -- bms_num_members()
 SELECT test_bms_num_members('(b)') AS result;
@@ -183,6 +172,7 @@ SELECT test_bms_num_members('(b 2 4 6 8 10)') AS result;
 
 -- test_bms_equal()
 SELECT test_bms_equal('(b)', '(b)') AS result;
+SELECT test_bms_equal(NULL, NULL) AS result;
 SELECT test_bms_equal('(b)', '(b 1 3 5)') AS result;
 SELECT test_bms_equal('(b 1 3 5)', '(b)') AS result;
 SELECT test_bms_equal('(b 1 3 5)', '(b 1 3 5)') AS result;
@@ -190,10 +180,6 @@ SELECT test_bms_equal('(b 1 3 5)', '(b 2 4 6)') AS result;
 -- Equal with different word counts
 SELECT test_bms_equal('(b 5)', '(b 100)') AS result;
 SELECT test_bms_equal('(b 5 10)', '(b 100 200 300)') AS result;
--- Test module checks
-SELECT test_bms_equal('(b 5)', NULL) AS result;
-SELECT test_bms_equal(NULL, '(b 5)') AS result;
-SELECT test_bms_equal(NULL, NULL) AS result;
 
 -- bms_compare()
 SELECT test_bms_compare('(b)', '(b)') AS result;
@@ -206,10 +192,6 @@ SELECT test_bms_compare(
          test_bms_add_range('(b)', 0, 63),
          test_bms_add_range('(b)', 0, 64)
        ) AS result;
--- Test module checks
-SELECT test_bms_compare('(b 5)', NULL) AS result;
-SELECT test_bms_compare(NULL, '(b 5)') AS result;
-SELECT test_bms_compare(NULL, NULL) AS result;
 
 -- bms_add_range()
 SELECT test_bms_add_range('(b)', -5, 10); -- error
@@ -228,13 +210,6 @@ SELECT length(test_bms_add_range('(b)', 1000, 1100)) AS result;
 -- Force word count expansion
 SELECT test_bms_add_range('(b 5)', 100, 105) AS result;
 SELECT length(test_bms_add_range('(b 1 2)', 200, 250)) AS result;
--- Test module checks
-SELECT test_bms_add_range('(b 5)', 5, NULL) AS result;
-SELECT test_bms_add_range('(b 5)', NULL, 10) AS result;
-SELECT test_bms_add_range('(b 5)', NULL, NULL) AS result;
-SELECT test_bms_add_range(NULL, 5, 10) AS result;
-SELECT test_bms_add_range(NULL, 10, 5) AS result;
-SELECT test_bms_add_range(NULL, NULL, NULL) AS result;
 
 -- bms_membership()
 SELECT test_bms_membership('(b)') AS result;
@@ -247,25 +222,19 @@ SELECT test_bms_membership(NULL) AS result;
 SELECT test_bms_is_empty(NULL) AS result;
 SELECT test_bms_is_empty('(b)') AS result;
 SELECT test_bms_is_empty('(b 1)') AS result;
--- Test module check
-SELECT test_bms_is_empty(NULL) AS result;
 
 -- bms_singleton_member()
-SELECT test_bms_singleton_member('(b)'); -- error
-SELECT test_bms_singleton_member('(b 1 2)'); -- error
+SELECT test_bms_singleton_member('(b)'); -- error empty set
+SELECT test_bms_singleton_member('(b 1 2)'); -- error multiple members
 SELECT test_bms_singleton_member('(b 42)') AS result;
--- Test module check
-SELECT test_bms_singleton_member(NULL) AS result;
 
 -- bms_get_singleton_member()
-SELECT test_bms_get_singleton_member('(b)', 1000);
--- Not a singleton, returns input default
-SELECT test_bms_get_singleton_member('(b 3 6)', 1000) AS result;
--- Singletone, returns sole member
-SELECT test_bms_get_singleton_member('(b 400)', 1000) AS result;
--- Test module checks
-SELECT test_bms_get_singleton_member('', 1000) AS result;
-SELECT test_bms_get_singleton_member(NULL, -1) AS result;
+-- Try with an empty set
+SELECT test_bms_get_singleton_member(NULL) AS result;
+-- Not a singleton, returns -1
+SELECT test_bms_get_singleton_member('(b 3 6)') AS result;
+-- Singleton, returns sole member
+SELECT test_bms_get_singleton_member('(b 400)') AS result;
 
 -- bms_next_member() and bms_prev_member()
 -- First member
@@ -286,14 +255,6 @@ SELECT test_bms_prev_member('(b 5 10 15 20)', 5) AS result;
 SELECT test_bms_prev_member('(b)', 100) AS result;
 -- Negative prevbit should result in highest possible bit in set
 SELECT test_bms_prev_member('(b 0 63 64 127)', -1) AS result;
--- Test module checks
-SELECT test_bms_next_member('', 5) AS result;
-SELECT test_bms_next_member('(b 5)', NULL) AS result;
-SELECT test_bms_next_member(NULL, 5) AS result;
-SELECT test_bms_next_member(NULL, NULL) AS result;
-SELECT test_bms_prev_member('', 5) AS result;
-SELECT test_bms_prev_member('(b 5)', NULL) AS result;
-SELECT test_bms_prev_member(NULL, 5) AS result;
 
 -- bms_hash_value()
 SELECT test_bms_hash_value('(b)') = 0 AS result;
@@ -306,10 +267,6 @@ SELECT test_bms_hash_value(NULL) AS result;
 SELECT test_bms_overlap('(b 1 3 5)', '(b 3 5 7)') AS result;
 SELECT test_bms_overlap('(b 1 3 5)', '(b 2 4 6)') AS result;
 SELECT test_bms_overlap('(b)', '(b 1 3 5)') AS result;
--- Test module checks
-SELECT test_bms_overlap('(b 5)', NULL) AS result;
-SELECT test_bms_overlap(NULL, '(b 5)') AS result;
-SELECT test_bms_overlap(NULL, NULL) AS result;
 
 -- bms_is_subset()
 SELECT test_bms_is_subset('(b)', '(b 1 3 5)') AS result;
@@ -350,16 +307,10 @@ SELECT test_bms_subset_compare('(b 1 2)', '(b 1 2 64)') AS result;
 SELECT test_bms_subset_compare('(b 64 200)', '(b 1 201)') AS result;
 SELECT test_bms_subset_compare('(b 1 64 65)', '(b 1 2 64)') AS result;
 SELECT test_bms_subset_compare('(b 2 64 128)', '(b 1 65)') AS result;
--- Test module checks
-SELECT test_bms_subset_compare('(b 5)', NULL) AS result;
-SELECT test_bms_subset_compare(NULL, '(b 5)') AS result;
-SELECT test_bms_subset_compare(NULL, NULL) AS result;
 
 -- bms_copy()
 SELECT test_bms_copy(NULL) AS result;
 SELECT test_bms_copy('(b 1 3 5 7)') AS result;
--- Test module check
-SELECT test_bms_copy(NULL) AS result;
 
 -- bms_add_members()
 SELECT test_bms_add_members('(b 1 3)', '(b 5 7)') AS result;
@@ -371,8 +322,6 @@ SELECT test_bitmap_hash('(b)') = 0 AS result;
 SELECT test_bitmap_hash('(b 1 3 5)') = test_bitmap_hash('(b 1 3 5)') AS result;
 SELECT test_bitmap_hash('(b 1 3 5)') = test_bms_hash_value('(b 1 3 5)') AS result;
 SELECT test_bitmap_hash('(b 1 3 5)') != test_bitmap_hash('(b 2 4 6)') AS result;
--- Test module check
-SELECT test_bitmap_hash(NULL) AS result;
 
 -- bitmap_match()
 SELECT test_bitmap_match('(b)', '(b)') AS result;
@@ -388,10 +337,6 @@ SELECT (test_bitmap_match('(b 1 3 5)', '(b 2 4 6)') = 0) =
         test_bms_equal('(b 1 3 5)', '(b 2 4 6)') AS result;
 SELECT (test_bitmap_match('(b)', '(b)') = 0) =
         test_bms_equal('(b)', '(b)') AS result;
--- Test module checks
-SELECT test_bitmap_match('(b 5)', NULL) AS result;
-SELECT test_bitmap_match(NULL, '(b 5)') AS result;
-SELECT test_bitmap_match(NULL, NULL) AS result;
 
 -- bms_overlap_list()
 SELECT test_bms_overlap_list('(b 0)', ARRAY[0]) AS result;
@@ -419,10 +364,6 @@ SELECT test_bms_nonempty_difference('(b 1 3 5)', '(b 1 3 5)') AS result;
 SELECT test_bms_nonempty_difference('(b 5)', '(b 100)') AS result;
 SELECT test_bms_nonempty_difference('(b 100)', '(b 5)') AS result;
 SELECT test_bms_nonempty_difference('(b 1 2)', '(b 50 100)') AS result;
--- Test module checks
-SELECT test_bms_nonempty_difference('(b 5)', NULL) AS result;
-SELECT test_bms_nonempty_difference(NULL, '(b 5)') AS result;
-SELECT test_bms_nonempty_difference(NULL, NULL) AS result;
 
 -- random operations
 SELECT test_random_operations(-1, 10000, 81920, 0) > 0 AS result;
diff --git a/src/test/modules/test_bitmapset/test_bitmapset--1.0.sql b/src/test/modules/test_bitmapset/test_bitmapset--1.0.sql
index b95c4d0dda5..227ecb5aa3b 100644
--- a/src/test/modules/test_bitmapset/test_bitmapset--1.0.sql
+++ b/src/test/modules/test_bitmapset/test_bitmapset--1.0.sql
@@ -68,7 +68,7 @@ CREATE FUNCTION test_bms_singleton_member(text)
 RETURNS integer STRICT
 AS 'MODULE_PATHNAME' LANGUAGE C;
 
-CREATE FUNCTION test_bms_get_singleton_member(text, integer)
+CREATE FUNCTION test_bms_get_singleton_member(text)
 RETURNS integer
 AS 'MODULE_PATHNAME' LANGUAGE C;
 
diff --git a/src/test/modules/test_bitmapset/test_bitmapset.c b/src/test/modules/test_bitmapset/test_bitmapset.c
index 2e821320836..06f15a5d065 100644
--- a/src/test/modules/test_bitmapset/test_bitmapset.c
+++ b/src/test/modules/test_bitmapset/test_bitmapset.c
@@ -26,7 +26,6 @@
 #include "nodes/pg_list.h"
 #include "utils/builtins.h"
 #include "utils/timestamp.h"
-#include "varatt.h"
 
 PG_MODULE_MAGIC;
 
@@ -88,101 +87,93 @@ PG_FUNCTION_INFO_V1(test_random_operations);
 #define BITMAPSET_TO_TEXT(bms) cstring_to_text(nodeToString(bms))
 #define TEXT_TO_BITMAPSET(str) ((Bitmapset *) stringToNode(text_to_cstring(str)))
 
+/* Helper macro to fetch Text parameters as Bitmapsets. SQL-NULL means empty set */
+#define PG_ARG_GETBITMAPSET(n) \
+	(PG_ARGISNULL(n) ? NULL : TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(n)))
+
+/*
+ * Helper macro to handle converting sets back to text, returning the
+ * resulting text representation of the set.
+ */
+#define PG_RETURN_BITMAPSET_AS_TEXT(bms) \
+	PG_RETURN_TEXT_P(BITMAPSET_TO_TEXT(bms))
+
 /*
  * Individual test functions for each bitmapset API function
+ *
+ * Primarily, we aim to keep these as close to simple wrapper functions as
+ * possible in order to publish the functions of bitmapset.c to the SQL layer
+ * with as little interference as possible.  We opt to return SQL NULL in
+ * cases where the input given to the SQL function isn't valid to pass to the
+ * underlying bitmapset.c function.  For example, we cannot do much useful
+ * testing if someone calls test_bms_make_singleton(NULL) since
+ * bms_make_singleton() expects an integer argument.
+ *
+ * For function arguments which are to be converted to Bitmapsets, we accept
+ * SQL NULL as a valid argument to mean an empty set.  Optionally, callers may
+ * pass '(b)'.
  */
 
 Datum
 test_bms_add_member(PG_FUNCTION_ARGS)
 {
+	Bitmapset  *bms;
 	int			member;
-	Bitmapset  *bms = NULL;
-	text	   *result;
 
 	if (PG_ARGISNULL(1))
-		PG_RETURN_NULL();
-
-	if (!PG_ARGISNULL(0))
-		bms = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
+		PG_RETURN_NULL();		/* invalid input */
 
+	bms = PG_ARG_GETBITMAPSET(0);
 	member = PG_GETARG_INT32(1);
-	bms = bms_add_member(bms, member);
-	result = BITMAPSET_TO_TEXT(bms);
 
-	if (bms)
-		bms_free(bms);
+	bms = bms_add_member(bms, member);
 
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_BITMAPSET_AS_TEXT(bms);
 }
 
 Datum
 test_bms_add_members(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms1 = NULL,
-			   *bms2 = NULL;
-	text	   *result;
-
-	if (!PG_ARGISNULL(0))
-		bms1 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
+	Bitmapset  *bms1 = PG_ARG_GETBITMAPSET(0);
+	Bitmapset  *bms2 = PG_ARG_GETBITMAPSET(1);
 
-	if (!PG_ARGISNULL(1))
-		bms2 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(1));
-
-	/* IMPORTANT: bms_add_members modifies/frees the first argument */
+	/* left input is recycled */
 	bms1 = bms_add_members(bms1, bms2);
 
-	if (bms2)
-		bms_free(bms2);
-
-	result = BITMAPSET_TO_TEXT(bms1);
-	bms_free(bms1);
-
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_BITMAPSET_AS_TEXT(bms1);
 }
 
 Datum
 test_bms_del_member(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms = NULL;
+	Bitmapset  *bms;
 	int32		member;
-	text	   *result;
 
 	if (PG_ARGISNULL(1))
-		PG_RETURN_NULL();
-
-	if (!PG_ARGISNULL(0))
-		bms = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
+		PG_RETURN_NULL();		/* invalid input */
 
+	bms = PG_ARG_GETBITMAPSET(0);
 	member = PG_GETARG_INT32(1);
-	bms = bms_del_member(bms, member);
 
-	if (bms_is_empty(bms))
-		PG_RETURN_NULL();
-
-	result = BITMAPSET_TO_TEXT(bms);
-	bms_free(bms);
+	bms = bms_del_member(bms, member);
 
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_BITMAPSET_AS_TEXT(bms);
 }
 
 Datum
 test_bms_is_member(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms = NULL;
+	Bitmapset  *bms;
 	int32		member;
 	bool		result;
 
 	if (PG_ARGISNULL(1))
-		PG_RETURN_BOOL(false);
-
-	if (!PG_ARGISNULL(0))
-		bms = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
+		PG_RETURN_NULL();		/* invalid input */
 
+	bms = PG_ARG_GETBITMAPSET(0);
 	member = PG_GETARG_INT32(1);
-	result = bms_is_member(member, bms);
 
-	if (bms)
-		bms_free(bms);
+	result = bms_is_member(member, bms);
 
 	PG_RETURN_BOOL(result);
 }
@@ -190,150 +181,89 @@ test_bms_is_member(PG_FUNCTION_ARGS)
 Datum
 test_bms_num_members(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms = NULL;
-	int			result = 0;
-
-	if (!PG_ARGISNULL(0))
-		bms = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
+	Bitmapset  *bms = PG_ARG_GETBITMAPSET(0);
+	int			result;
 
 	result = bms_num_members(bms);
 
-	if (bms)
-		bms_free(bms);
-
 	PG_RETURN_INT32(result);
 }
 
 Datum
 test_bms_make_singleton(PG_FUNCTION_ARGS)
 {
-	int32		member;
 	Bitmapset  *bms;
-	text	   *result;
+	int32		member;
 
 	if (PG_ARGISNULL(0))
-		PG_RETURN_NULL();
+		PG_RETURN_NULL();		/* invalid input */
 
 	member = PG_GETARG_INT32(0);
 	bms = bms_make_singleton(member);
 
-	result = BITMAPSET_TO_TEXT(bms);
-	bms_free(bms);
-
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_BITMAPSET_AS_TEXT(bms);
 }
 
 Datum
 test_bms_copy(PG_FUNCTION_ARGS)
 {
-	text	   *bms_data;
-	Bitmapset  *bms = NULL;
+	Bitmapset  *bms = PG_ARG_GETBITMAPSET(0);
 	Bitmapset  *copy_bms;
-	text	   *result;
-
-	if (PG_ARGISNULL(0))
-		PG_RETURN_NULL();
 
-	bms_data = PG_GETARG_TEXT_PP(0);
-	bms = TEXT_TO_BITMAPSET(bms_data);
 	copy_bms = bms_copy(bms);
-	result = BITMAPSET_TO_TEXT(copy_bms);
 
-	if (bms)
-		bms_free(bms);
-	if (copy_bms)
-		bms_free(copy_bms);
-
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_BITMAPSET_AS_TEXT(copy_bms);
 }
 
 Datum
 test_bms_equal(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms1 = NULL,
-			   *bms2 = NULL;
+	Bitmapset  *bms1 = PG_ARG_GETBITMAPSET(0);
+	Bitmapset  *bms2 = PG_ARG_GETBITMAPSET(1);
 	bool		result;
 
-	if (!PG_ARGISNULL(0))
-		bms1 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
-
-	if (!PG_ARGISNULL(1))
-		bms2 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(1));
-
 	result = bms_equal(bms1, bms2);
 
-	if (bms1)
-		bms_free(bms1);
-	if (bms2)
-		bms_free(bms2);
-
 	PG_RETURN_BOOL(result);
 }
 
 Datum
 test_bms_union(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms1 = NULL,
-			   *bms2 = NULL;
+	Bitmapset  *bms1 = PG_ARG_GETBITMAPSET(0);
+	Bitmapset  *bms2 = PG_ARG_GETBITMAPSET(1);
 	Bitmapset  *result_bms;
-	text	   *result;
-
-	if (!PG_ARGISNULL(0))
-		bms1 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
-
-	if (!PG_ARGISNULL(1))
-		bms2 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(1));
 
 	result_bms = bms_union(bms1, bms2);
 
-	if (bms1)
-		bms_free(bms1);
-	if (bms2)
-		bms_free(bms2);
-
-	if (result_bms == NULL)
-		PG_RETURN_NULL();
-
-	result = BITMAPSET_TO_TEXT(result_bms);
-	bms_free(result_bms);
-
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_BITMAPSET_AS_TEXT(result_bms);
 }
 
 Datum
 test_bms_membership(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms = NULL;
+	Bitmapset  *bms = PG_ARG_GETBITMAPSET(0);
 	BMS_Membership result;
 
-	if (PG_ARGISNULL(0))
-		PG_RETURN_INT32(BMS_EMPTY_SET);
-
-	bms = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
 	result = bms_membership(bms);
 
-	if (bms)
-		bms_free(bms);
-
 	PG_RETURN_INT32((int32) result);
 }
 
 Datum
 test_bms_next_member(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms = NULL;
+	Bitmapset  *bms;
 	int32		prevmember;
 	int			result;
 
-	if (PG_ARGISNULL(0) || PG_ARGISNULL(1))
-		PG_RETURN_INT32(-2);
+	if (PG_ARGISNULL(1))
+		PG_RETURN_NULL();		/* invalid input */
 
-	bms = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
+	bms = PG_ARG_GETBITMAPSET(0);
 	prevmember = PG_GETARG_INT32(1);
-	result = bms_next_member(bms, prevmember);
 
-	if (bms)
-		bms_free(bms);
+	result = bms_next_member(bms, prevmember);
 
 	PG_RETURN_INT32(result);
 }
@@ -341,212 +271,115 @@ test_bms_next_member(PG_FUNCTION_ARGS)
 Datum
 test_bms_intersect(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms1 = NULL,
-			   *bms2 = NULL;
+	Bitmapset  *bms1 = PG_ARG_GETBITMAPSET(0);
+	Bitmapset  *bms2 = PG_ARG_GETBITMAPSET(1);
 	Bitmapset  *result_bms;
-	text	   *result;
-
-	if (!PG_ARGISNULL(0))
-		bms1 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
-
-	if (!PG_ARGISNULL(1))
-		bms2 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(1));
 
 	result_bms = bms_intersect(bms1, bms2);
 
-	if (bms1)
-		bms_free(bms1);
-	if (bms2)
-		bms_free(bms2);
-
-	if (result_bms == NULL)
-		PG_RETURN_NULL();
-
-	result = BITMAPSET_TO_TEXT(result_bms);
-	bms_free(result_bms);
-
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_BITMAPSET_AS_TEXT(result_bms);
 }
 
 Datum
 test_bms_difference(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms1 = NULL,
-			   *bms2 = NULL;
+	Bitmapset  *bms1 = PG_ARG_GETBITMAPSET(0);
+	Bitmapset  *bms2 = PG_ARG_GETBITMAPSET(1);
 	Bitmapset  *result_bms;
-	text	   *result;
-
-	if (!PG_ARGISNULL(0))
-		bms1 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
-
-	if (!PG_ARGISNULL(1))
-		bms2 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(1));
 
 	result_bms = bms_difference(bms1, bms2);
 
-	if (bms1)
-		bms_free(bms1);
-	if (bms2)
-		bms_free(bms2);
-
-	if (result_bms == NULL)
-		PG_RETURN_NULL();
-
-	result = BITMAPSET_TO_TEXT(result_bms);
-	bms_free(result_bms);
-
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_BITMAPSET_AS_TEXT(result_bms);
 }
 
 Datum
 test_bms_compare(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms1 = NULL,
-			   *bms2 = NULL;
+	Bitmapset  *bms1 = PG_ARG_GETBITMAPSET(0);
+	Bitmapset  *bms2 = PG_ARG_GETBITMAPSET(1);
 	int			result;
 
-	if (!PG_ARGISNULL(0))
-		bms1 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
-
-	if (!PG_ARGISNULL(1))
-		bms2 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(1));
-
 	result = bms_compare(bms1, bms2);
 
-	if (bms1)
-		bms_free(bms1);
-	if (bms2)
-		bms_free(bms2);
-
 	PG_RETURN_INT32(result);
 }
 
 Datum
 test_bms_is_empty(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms = NULL;
+	Bitmapset  *bms = PG_ARG_GETBITMAPSET(0);
 	bool		result;
 
-	if (!PG_ARGISNULL(0))
-		bms = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
-
 	result = bms_is_empty(bms);
 
-	if (bms)
-		bms_free(bms);
-
 	PG_RETURN_BOOL(result);
 }
 
 Datum
 test_bms_is_subset(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms1 = NULL,
-			   *bms2 = NULL;
+	Bitmapset  *bms1 = PG_ARG_GETBITMAPSET(0);
+	Bitmapset  *bms2 = PG_ARG_GETBITMAPSET(1);
 	bool		result;
 
-	if (!PG_ARGISNULL(0))
-		bms1 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
-
-	if (!PG_ARGISNULL(1))
-		bms2 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(1));
-
 	result = bms_is_subset(bms1, bms2);
 
-	if (bms1)
-		bms_free(bms1);
-	if (bms2)
-		bms_free(bms2);
-
 	PG_RETURN_BOOL(result);
 }
 
 Datum
 test_bms_subset_compare(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms1 = NULL,
-			   *bms2 = NULL;
+	Bitmapset  *bms1 = PG_ARG_GETBITMAPSET(0);
+	Bitmapset  *bms2 = PG_ARG_GETBITMAPSET(1);
 	BMS_Comparison result;
 
-	if (!PG_ARGISNULL(0))
-		bms1 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
-
-	if (!PG_ARGISNULL(1))
-		bms2 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(1));
-
 	result = bms_subset_compare(bms1, bms2);
 
-	if (bms1)
-		bms_free(bms1);
-	if (bms2)
-		bms_free(bms2);
-
 	PG_RETURN_INT32((int32) result);
 }
 
 Datum
 test_bms_singleton_member(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms = NULL;
+	Bitmapset  *bms = PG_ARG_GETBITMAPSET(0);
 	int			result;
 
-	if (!PG_ARGISNULL(0))
-		bms = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
-
 	result = bms_singleton_member(bms);
 
-	if (bms)
-		bms_free(bms);
-
 	PG_RETURN_INT32(result);
 }
 
 Datum
 test_bms_get_singleton_member(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms = NULL;
-	int32		default_member = PG_GETARG_INT32(1);
-	bool		success;
-	int			member = -1;
-
-	if (PG_ARGISNULL(0))
-		PG_RETURN_INT32(default_member);
-
-	bms = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
+	Bitmapset  *bms = PG_ARG_GETBITMAPSET(0);
+	int			member;
 
 	/*
-	 * bms_get_singleton_member returns bool and stores result in member
-	 * pointer
+	 * Keep this simple.  Return -1 when we detect the set isn't a singleton
+	 * set, otherwise return the singleton member.
 	 */
-	success = bms_get_singleton_member(bms, &member);
-	bms_free(bms);
-
-	if (success)
-		PG_RETURN_INT32(member);
+	if (!bms_get_singleton_member(bms, &member))
+		member = -1;
 
-	PG_RETURN_INT32(default_member);
+	PG_RETURN_INT32(member);
 }
 
 Datum
 test_bms_prev_member(PG_FUNCTION_ARGS)
 {
-	text	   *bms_data;
-	Bitmapset  *bms = NULL;
+	Bitmapset  *bms;
 	int32		prevmember;
 	int			result;
 
-	if (PG_ARGISNULL(0))
-		PG_RETURN_INT32(-2);
+	if (PG_ARGISNULL(1))
+		PG_RETURN_NULL();		/* invalid input */
 
-	bms_data = PG_GETARG_TEXT_PP(0);
+	bms = PG_ARG_GETBITMAPSET(0);
 	prevmember = PG_GETARG_INT32(1);
 
-	if (VARSIZE_ANY_EXHDR(bms_data) == 0)
-		PG_RETURN_INT32(-2);
-
-	bms = TEXT_TO_BITMAPSET(bms_data);
 	result = bms_prev_member(bms, prevmember);
-	bms_free(bms);
 
 	PG_RETURN_INT32(result);
 }
@@ -554,75 +387,57 @@ test_bms_prev_member(PG_FUNCTION_ARGS)
 Datum
 test_bms_overlap(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms1 = NULL,
-			   *bms2 = NULL;
+	Bitmapset  *bms1 = PG_ARG_GETBITMAPSET(0);
+	Bitmapset  *bms2 = PG_ARG_GETBITMAPSET(1);
 	bool		result;
 
-	if (!PG_ARGISNULL(0))
-		bms1 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
-
-	if (!PG_ARGISNULL(1))
-		bms2 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(1));
-
 	result = bms_overlap(bms1, bms2);
 
-	if (bms1)
-		bms_free(bms1);
-	if (bms2)
-		bms_free(bms2);
-
 	PG_RETURN_BOOL(result);
 }
 
 Datum
 test_bms_overlap_list(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms = NULL;
+	Bitmapset  *bms;
 	ArrayType  *array;
 	List	   *int_list = NIL;
 	bool		result;
-	Datum	   *elem_datums;
-	bool	   *elem_nulls;
+	Datum	   *elem_datums = NULL;
+	bool	   *elem_nulls = NULL;
 	int			elem_count;
 	int			i;
 
-	if (PG_ARGISNULL(0))
-		PG_RETURN_BOOL(false);
-
-	bms = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
+	bms = PG_ARG_GETBITMAPSET(0);
 
-	if (PG_ARGISNULL(1))
+	if (!PG_ARGISNULL(1))
 	{
-		if (bms)
-			bms_free(bms);
-		PG_RETURN_BOOL(false);
-	}
+		array = PG_GETARG_ARRAYTYPE_P(1);
 
-	array = PG_GETARG_ARRAYTYPE_P(1);
+		deconstruct_array(array,
+						  INT4OID, sizeof(int32), true, 'i',
+						  &elem_datums, &elem_nulls, &elem_count);
 
-	deconstruct_array(array,
-					  INT4OID, sizeof(int32), true, 'i',
-					  &elem_datums, &elem_nulls, &elem_count);
-
-	for (i = 0; i < elem_count; i++)
-	{
-		if (!elem_nulls[i])
+		for (i = 0; i < elem_count; i++)
 		{
-			int32		member = DatumGetInt32(elem_datums[i]);
+			if (!elem_nulls[i])
+			{
+				int32		member = DatumGetInt32(elem_datums[i]);
 
-			int_list = lappend_int(int_list, member);
+				int_list = lappend_int(int_list, member);
+			}
 		}
 	}
 
 	result = bms_overlap_list(bms, int_list);
 
-	if (bms)
-		bms_free(bms);
-
 	list_free(int_list);
 
-	pfree(elem_datums);
-	pfree(elem_nulls);
+	if (elem_datums)
+		pfree(elem_datums);
+
+	if (elem_nulls)
+		pfree(elem_nulls);
 
 	PG_RETURN_BOOL(result);
 }
@@ -630,47 +445,29 @@ test_bms_overlap_list(PG_FUNCTION_ARGS)
 Datum
 test_bms_nonempty_difference(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms1 = NULL,
-			   *bms2 = NULL;
+	Bitmapset  *bms1 = PG_ARG_GETBITMAPSET(0);
+	Bitmapset  *bms2 = PG_ARG_GETBITMAPSET(1);
 	bool		result;
 
-	if (!PG_ARGISNULL(0))
-		bms1 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
-
-	if (!PG_ARGISNULL(1))
-		bms2 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(1));
-
 	result = bms_nonempty_difference(bms1, bms2);
 
-	if (bms1)
-		bms_free(bms1);
-	if (bms2)
-		bms_free(bms2);
-
 	PG_RETURN_BOOL(result);
 }
 
 Datum
 test_bms_member_index(PG_FUNCTION_ARGS)
 {
-	text	   *bms_data;
-	Bitmapset  *bms = NULL;
+	Bitmapset  *bms;
 	int32		member;
 	int			result;
 
-	if (PG_ARGISNULL(0))
-		PG_RETURN_INT32(-1);
+	if (PG_ARGISNULL(1))
+		PG_RETURN_NULL();		/* invalid input */
 
-	bms_data = PG_GETARG_TEXT_PP(0);
+	bms = PG_ARG_GETBITMAPSET(0);
 	member = PG_GETARG_INT32(1);
 
-	if (VARSIZE_ANY_EXHDR(bms_data) == 0)
-		PG_RETURN_INT32(-1);
-
-	bms = TEXT_TO_BITMAPSET(bms_data);
-
 	result = bms_member_index(bms, member);
-	bms_free(bms);
 
 	PG_RETURN_INT32(result);
 }
@@ -678,191 +475,92 @@ test_bms_member_index(PG_FUNCTION_ARGS)
 Datum
 test_bms_add_range(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms = NULL;
+	Bitmapset  *bms;
 	int32		lower,
 				upper;
-	text	   *result;
 
 	if (PG_ARGISNULL(1) || PG_ARGISNULL(2))
-		PG_RETURN_NULL();
-
-	if (!PG_ARGISNULL(0))
-		bms = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
+		PG_RETURN_NULL();		/* invalid input */
 
+	bms = PG_ARG_GETBITMAPSET(0);
 	lower = PG_GETARG_INT32(1);
 	upper = PG_GETARG_INT32(2);
 
-	/* Check for invalid range */
-	if (upper < lower)
-	{
-		if (bms)
-			bms_free(bms);
-		PG_RETURN_NULL();
-	}
-
 	bms = bms_add_range(bms, lower, upper);
 
-	result = BITMAPSET_TO_TEXT(bms);
-	if (bms)
-		bms_free(bms);
-
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_BITMAPSET_AS_TEXT(bms);
 }
 
 Datum
 test_bms_int_members(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms1 = NULL,
-			   *bms2 = NULL;
-	text	   *result;
-
-	if (!PG_ARGISNULL(0))
-		bms1 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
-
-	if (!PG_ARGISNULL(1))
-		bms2 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(1));
+	Bitmapset  *bms1 = PG_ARG_GETBITMAPSET(0);
+	Bitmapset  *bms2 = PG_ARG_GETBITMAPSET(1);
 
+	/* left input gets recycled */
 	bms1 = bms_int_members(bms1, bms2);
 
-	if (bms2)
-		bms_free(bms2);
-
-	if (bms1 == NULL)
-		PG_RETURN_NULL();
-
-	result = BITMAPSET_TO_TEXT(bms1);
-
-	if (bms1)
-		bms_free(bms1);
-
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_BITMAPSET_AS_TEXT(bms1);
 }
 
 Datum
 test_bms_del_members(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms1 = NULL,
-			   *bms2 = NULL;
-	Bitmapset  *result_bms;
-	text	   *result;
+	Bitmapset  *bms1 = PG_ARG_GETBITMAPSET(0);
+	Bitmapset  *bms2 = PG_ARG_GETBITMAPSET(1);
 
-	if (!PG_ARGISNULL(0))
-		bms1 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
+	/* left input gets recycled */
+	bms1 = bms_del_members(bms1, bms2);
 
-	if (!PG_ARGISNULL(1))
-		bms2 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(1));
-
-	/* IMPORTANT: bms_del_members modifies/frees the first argument */
-	result_bms = bms_del_members(bms1, bms2);
-
-	/* bms1 is now invalid, do not free it */
-
-	if (bms2)
-		bms_free(bms2);
-
-	if (result_bms == NULL)
-		PG_RETURN_NULL();
-
-	result = BITMAPSET_TO_TEXT(result_bms);
-	bms_free(result_bms);
-
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_BITMAPSET_AS_TEXT(bms1);
 }
 
 Datum
 test_bms_replace_members(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms1 = NULL,
-			   *bms2 = NULL;
-	Bitmapset  *result_bms;
-	text	   *result;
-
-	if (!PG_ARGISNULL(0))
-		bms1 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
-
-	if (!PG_ARGISNULL(1))
-		bms2 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(1));
+	Bitmapset  *bms1 = PG_ARG_GETBITMAPSET(0);
+	Bitmapset  *bms2 = PG_ARG_GETBITMAPSET(1);
 
-	/* IMPORTANT: bms_replace_members modifies/frees the first argument */
-	result_bms = bms_replace_members(bms1, bms2);
+	/* left input gets recycled */
+	bms1 = bms_replace_members(bms1, bms2);
 
-	/* bms1 is now invalid, do not free it */
-
-	if (bms2)
-		bms_free(bms2);
-
-	if (result_bms == NULL)
-		PG_RETURN_NULL();
-
-	result = BITMAPSET_TO_TEXT(result_bms);
-	bms_free(result_bms);
-
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_BITMAPSET_AS_TEXT(bms1);
 }
 
 Datum
 test_bms_join(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms1 = NULL,
-			   *bms2 = NULL;
+	Bitmapset  *bms1 = PG_ARG_GETBITMAPSET(0);
+	Bitmapset  *bms2 = PG_ARG_GETBITMAPSET(1);
 	Bitmapset  *result_bms;
-	text	   *result;
-
-	if (!PG_ARGISNULL(0))
-		bms1 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
 
-	if (!PG_ARGISNULL(1))
-		bms2 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(1));
-
-	/* IMPORTANT: bms_join may recycle either input arguments */
+	/* either input can be recycled */
 	result_bms = bms_join(bms1, bms2);
 
-	/* bms1 and bms2 may have been recycled! Do not free any of them. */
-
-	if (result_bms == NULL)
-		PG_RETURN_NULL();
-
-	result = BITMAPSET_TO_TEXT(result_bms);
-	bms_free(result_bms);
+	/* memory cleanup seems more tricky than it's worth here */
 
-	PG_RETURN_TEXT_P(result);
+	PG_RETURN_BITMAPSET_AS_TEXT(result_bms);
 }
 
 Datum
 test_bms_hash_value(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms = NULL;
+	Bitmapset  *bms = PG_ARG_GETBITMAPSET(0);
 	uint32		hash_result;
 
-	if (!PG_ARGISNULL(0))
-		bms = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
-
 	hash_result = bms_hash_value(bms);
 
-	if (bms)
-		bms_free(bms);
-
 	PG_RETURN_INT32(hash_result);
 }
 
 Datum
 test_bitmap_hash(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms = NULL;
-	Bitmapset  *bms_ptr;
+	Bitmapset  *bms = PG_ARG_GETBITMAPSET(0);
 	uint32		hash_result;
 
-	if (!PG_ARGISNULL(0))
-		bms = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
-
-	bms_ptr = bms;
-
 	/* Call bitmap_hash */
-	hash_result = bitmap_hash(&bms_ptr, sizeof(Bitmapset *));
-
-	/* Clean up */
-	if (!PG_ARGISNULL(0) && bms_ptr)
-		bms_free(bms_ptr);
+	hash_result = bitmap_hash(&bms, sizeof(Bitmapset *));
 
 	PG_RETURN_INT32(hash_result);
 }
@@ -870,30 +568,12 @@ test_bitmap_hash(PG_FUNCTION_ARGS)
 Datum
 test_bitmap_match(PG_FUNCTION_ARGS)
 {
-	Bitmapset  *bms1 = NULL,
-			   *bms2 = NULL;
-	Bitmapset  *bms_ptr1,
-			   *bms_ptr2;
+	Bitmapset  *bms1 = PG_ARG_GETBITMAPSET(0);
+	Bitmapset  *bms2 = PG_ARG_GETBITMAPSET(1);
 	int			match_result;
 
-	if (!PG_ARGISNULL(0))
-		bms1 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(0));
-
-	if (!PG_ARGISNULL(1))
-		bms2 = TEXT_TO_BITMAPSET(PG_GETARG_TEXT_PP(1));
-
-	/* Set up pointers to the Bitmapsets */
-	bms_ptr1 = bms1;
-	bms_ptr2 = bms2;
-
 	/* Call bitmap_match with addresses of the Bitmapset pointers */
-	match_result = bitmap_match(&bms_ptr1, &bms_ptr2, sizeof(Bitmapset *));
-
-	/* Clean up */
-	if (bms1)
-		bms_free(bms1);
-	if (bms2)
-		bms_free(bms2);
+	match_result = bitmap_match(&bms1, &bms2, sizeof(Bitmapset *));
 
 	PG_RETURN_INT32(match_result);
 }
@@ -1031,8 +711,7 @@ test_random_operations(PG_FUNCTION_ARGS)
 		total_ops++;
 	}
 
-	if (bms)
-		bms_free(bms);
+	bms_free(bms);
 
 	PG_RETURN_INT32(total_ops);
 }