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Merge pull request #277 from jmid/shrinker-adjustments
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Shrinker adjustments
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@jmid
jmid authored May 2, 2023
2 parents cab908d + ea5bd22 commit aeb9bd0
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2 changes: 2 additions & 0 deletions CHANGELOG.md
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Expand Up @@ -9,6 +9,8 @@
- fix issue with `ppx_deriving_qcheck` deriving a generator with unbound
`gen` for recursive types [#269](https://github.com/c-cube/qcheck/issues/269)
and a related issue when deriving a generator for a record type
- fix #241 causing `QCheck.Shrink.int*` to emit duplicates, also affecting `QCheck.Shrink.{char,string}`
- fix a cornercase where `Shrink.list_spine` would emit duplicates
- ...

## 0.20
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14 changes: 7 additions & 7 deletions src/core/QCheck.ml
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Expand Up @@ -677,26 +677,26 @@ module Shrink = struct
let y = ref x in
(* try some divisors *)
while !y < -2 || !y >2 do y := !y / 2; yield (x - !y); done; (* fast path *)
if x>0 then yield (x-1);
if x<0 then yield (x+1);
if x = 1 || (x>0 && !y <> 1) then yield (x-1);
if x = -1 || (x<0 && !y <> -1) then yield (x+1);
()

let int32 x yield =
let open Int32 in
let y = ref x in
(* try some divisors *)
while !y < -2l || !y > 2l do y := div !y 2l; yield (sub x !y); done; (* fast path *)
if x>0l then yield (pred x);
if x<0l then yield (succ x);
if x = 1l || (x>0l && !y <> 1l) then yield (pred x);
if x = -1l || (x<0l && !y <> -1l) then yield (succ x);
()

let int64 x yield =
let open Int64 in
let y = ref x in
(* try some divisors *)
while !y < -2L || !y > 2L do y := div !y 2L; yield (sub x !y); done; (* fast path *)
if x>0L then yield (pred x);
if x<0L then yield (succ x);
if x = 1L || (x>0L && !y <> 1L) then yield (pred x);
if x = -1L || (x<0L && !y <> -1L) then yield (succ x);
()

(* aggressive shrinker for integers,
Expand Down Expand Up @@ -760,7 +760,7 @@ module Shrink = struct
match l with
| [] -> ()
| [_] -> yield []
| [x;y] -> yield []; yield [x]; yield [y]
| [x;y] -> yield []; yield [x]; if x <> y then yield [y]
| _::_ ->
let len = List.length l in
let xs,ys = split l ((1 + len) / 2) [] in
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1 change: 0 additions & 1 deletion test/core/QCheck_expect_test.expected.32
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Expand Up @@ -74,7 +74,6 @@ random seed: 1234
[1; 1]
[]
[1]
[1]
[0; 1]
[1; 0]

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1 change: 0 additions & 1 deletion test/core/QCheck_expect_test.expected.64
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Expand Up @@ -106,7 +106,6 @@ random seed: 1234
[1; 1]
[]
[1]
[1]
[0; 1]
[1; 0]

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1 change: 0 additions & 1 deletion test/core/QCheck_expect_test.expected.ocaml5
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Expand Up @@ -116,7 +116,6 @@ random seed: 1234
[2; 2]
[]
[2]
[2]
[1; 2]
[2; 1]

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59 changes: 46 additions & 13 deletions test/core/QCheck_unit_tests.ml
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Expand Up @@ -19,29 +19,29 @@ module Shrink = struct

let test_int () =
List.iter (alco_check Alcotest.int (trace_false Shrink.int) "on repeated failure")
[ ("int 100", 100, [50; 75; 88; 94; 97; 99; 99]); (*WTF?*)
("int 1000", 1000, [500; 750; 875; 938; 969; 985; 993; 997; 999; 999]); (*WTF?*)
("int (-26)", -26, [-13; -20; -23; -25; -25]) ]; (*WTF?*)
[ ("int 100", 100, [50; 75; 88; 94; 97; 99]);
("int 1000", 1000, [500; 750; 875; 938; 969; 985; 993; 997; 999]);
("int (-26)", -26, [-13; -20; -23; -25]) ];
List.iter (alco_check Alcotest.int (trace_true Shrink.int) "on repeated success")
[ ("int 100", 100, [50; 25; 13; 7; 4; 2; 1; 0]);
("int 1000", 1000, [500; 250; 125; 63; 32; 16; 8; 4; 2; 1; 0]);
("int (-26)", -26, [-13; -7; -4; -2; -1; 0]) ]

let test_int32 () =
List.iter (alco_check Alcotest.int32 (trace_false Shrink.int32) "on repeated failure")
[ ("int 100", 100l, [50l; 75l; 88l; 94l; 97l; 99l; 99l]);
("int 1000", 1000l, [500l; 750l; 875l; 938l; 969l; 985l; 993l; 997l; 999l; 999l]);
("int (-26)", -26l, [-13l; -20l; -23l; -25l; -25l]) ];
[ ("int 100", 100l, [50l; 75l; 88l; 94l; 97l; 99l]);
("int 1000", 1000l, [500l; 750l; 875l; 938l; 969l; 985l; 993l; 997l; 999l]);
("int (-26)", -26l, [-13l; -20l; -23l; -25l]) ];
List.iter (alco_check Alcotest.int32 (trace_true Shrink.int32) "on repeated success")
[ ("int 100", 100l, [50l; 25l; 13l; 7l; 4l; 2l; 1l; 0l]);
("int 1000", 1000l, [500l; 250l; 125l; 63l; 32l; 16l; 8l; 4l; 2l; 1l; 0l]);
("int (-26)", -26l, [-13l; -7l; -4l; -2l; -1l; 0l]) ]

let test_int64 () =
List.iter (alco_check Alcotest.int64 (trace_false Shrink.int64) "on repeated failure")
[ ("int 100", 100L, [50L; 75L; 88L; 94L; 97L; 99L; 99L]);
("int 1000", 1000L, [500L; 750L; 875L; 938L; 969L; 985L; 993L; 997L; 999L; 999L]);
("int (-26)", -26L, [-13L; -20L; -23L; -25L; -25L]) ];
[ ("int 100", 100L, [50L; 75L; 88L; 94L; 97L; 99L]);
("int 1000", 1000L, [500L; 750L; 875L; 938L; 969L; 985L; 993L; 997L; 999L]);
("int (-26)", -26L, [-13L; -20L; -23L; -25L]) ];
List.iter (alco_check Alcotest.int64 (trace_true Shrink.int64) "on repeated success")
[ ("int 100", 100L, [50L; 25L; 13L; 7L; 4L; 2L; 1L; 0L]);
("int 1000", 1000L, [500L; 250L; 125L; 63L; 32L; 16L; 8L; 4L; 2L; 1L; 0L]);
Expand All @@ -50,9 +50,9 @@ module Shrink = struct
let test_char () =
List.iter (alco_check Alcotest.char (trace_false Shrink.char) "on repeated failure")
[ ("char 'a'", 'a', []);
("char 'z'", 'z', ['n'; 't'; 'w'; 'y'; 'y']); (*WTF?*)
("char 'z'", 'z', ['n'; 't'; 'w'; 'y']);
("char 'A'", 'A', ['Q'; 'I'; 'E'; 'C'; 'B']);
("char '~'", '~', ['p'; 'w'; '{'; '}'; '}']) ]; (*WTF?*)
("char '~'", '~', ['p'; 'w'; '{'; '}']) ];
List.iter (alco_check Alcotest.char (trace_true Shrink.char) "on repeated success")
[ ("char 'a'", 'a', []);
("char 'z'", 'z', ['n'; 'h'; 'e'; 'c'; 'b'; 'a']);
Expand All @@ -72,22 +72,55 @@ module Shrink = struct
[ ("char 'A'", 'A', ['Q'; 'I'; 'E'; 'C'; 'B']);
("char 'a'", 'a', []);
("char ' '", ' ', ['@'; '0'; '('; '$'; '"'; '!']);
("char '~'", '~', ['p'; 'w'; '{'; '}'; '}']); (*WTF?*)
("char '\\n'", '\n', ['p'; 'w'; '{'; '}'; '}']); ]; (*WTF?*)
("char '~'", '~', ['p'; 'w'; '{'; '}']);
("char '\\n'", '\n', ['p'; 'w'; '{'; '}']); ];
List.iter (alco_check Alcotest.char (trace_true Shrink.char_printable) "on repeated success")
[ ("char 'A'", 'A', ['Q'; 'Y'; ']'; '_'; '`'; 'a']);
("char 'a'", 'a', []);
("char ' '", ' ', ['@'; 'P'; 'X'; '\\'; '^'; '_'; '`'; 'a']);
("char '~'", '~', ['p'; 'i'; 'e'; 'c'; 'b'; 'a']);
("char '\\n'", '\n', ['p'; 'i'; 'e'; 'c'; 'b'; 'a']); ]

let test_string () =
List.iter (alco_check Alcotest.string (trace_false Shrink.string) "on repeated failure")
[ ("string \"\"", "", []);
("string \"a\"", "a", [""]);
("string \"aa\"", "aa", [""; "a"]);
("string \"aaaa\"", "aaaa", ["aa"; "aa"; "aaa"]);
("string \"abcd\"", "abcd", ["ab"; "cd"; "acd"; "bcd"; "aacd"; "abbd"; "abcc"]);
("string \"E'*\"", "E'*", ["E'"; "*"; "E*"; "'*"; "S'*"; "L'*"; "H'*"; "F'*"; "ED*";
"E5*"; "E.*"; "E**"; "E(*"; "E'E"; "E'7"; "E'0"; "E'-"; "E'+"]);
("string \"vi5x92xgG\"", "vi5x92xgG", (* A less exhaustive string shrinker would be preferable *)
["vi5x9"; "vi52xgG"; "vix92xgG"; "5x92xgG";
"v5x92xgG"; "i5x92xgG"; "li5x92xgG"; "qi5x92xgG"; "ti5x92xgG"; "ui5x92xgG";
"ve5x92xgG"; "vg5x92xgG"; "vh5x92xgG";
"viKx92xgG"; "vi@x92xgG"; "vi:x92xgG"; "vi7x92xgG"; "vi6x92xgG";
"vi5m92xgG"; "vi5s92xgG"; "vi5v92xgG"; "vi5w92xgG";
"vi5xM2xgG"; "vi5xC2xgG"; "vi5x>2xgG"; "vi5x;2xgG"; "vi5x:2xgG";
"vi5x9IxgG"; "vi5x9=xgG"; "vi5x97xgG"; "vi5x94xgG"; "vi5x93xgG";
"vi5x92mgG"; "vi5x92sgG"; "vi5x92vgG"; "vi5x92wgG";
"vi5x92xdG"; "vi5x92xfG";
"vi5x92xgT"; "vi5x92xgM"; "vi5x92xgJ"; "vi5x92xgH"]);
("string \"~~~~\"", "~~~~", ["~~"; "~~"; "~~~"; "p~~~"; "w~~~"; "{~~~"; "}~~~"; "~p~~";
"~w~~"; "~{~~"; "~}~~"; "~~p~"; "~~w~"; "~~{~"; "~~}~";
"~~~p"; "~~~w"; "~~~{"; "~~~}"]); ];
List.iter (alco_check Alcotest.string (trace_true Shrink.string) "on repeated success")
[ ("string \"\"", "", []);
("string \"a\"", "a", [""]);
("string \"aa\"", "aa", [""]);
("string \"aaaa\"", "aaaa", ["aa"; ""]);
("string \"abcd\"", "abcd", ["ab"; ""]);
("string \"E'*\"", "E'*", ["E'"; ""]);
("string \"vi5x92xgG\"", "vi5x92xgG", ["vi5x9"; "vi5"; "vi"; ""]); ]

let tests = ("Shrink", Alcotest.[
test_case "int" `Quick test_int;
test_case "int32" `Quick test_int32;
test_case "int64" `Quick test_int64;
test_case "char" `Quick test_char;
test_case "char_numeral" `Quick test_char_numeral;
test_case "char_printable" `Quick test_char_printable;
test_case "string" `Quick test_string;
])
end

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