aboutsummaryrefslogtreecommitdiffstats
path: root/tests/check.py
blob: 3669fdbe3505c04776c4b5e43e6bc8909d209ef5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
#!/usr/bin/env python3
"""Vega checks: one aup spec, three surfaces.

1. CLI and NUI: examples/todo.aup under random adds, moves, toggles, urgent
   marks and removals prints exactly what a reference Python model of the app
   and of Vega's conventions says (lines for pipes, sentences for speech),
   including failed events on an empty list.
2. TUI: the same runs drawn at several sizes keep the focused row on screen
   with the least scrolling, show the rows around it in order, right-align
   badges by display width (Hangul, CJK and emoji take two cells, combining
   marks none), and evaluate only the cells on screen: a frame costs the
   title, the field, the focus and three cells per visible row, however long
   the list is.
3. Tables: examples/scores.aup aligns its columns by display width and marks
   row tones.
4. Every aup example runs on every surface under random keys without a crash.
5. Stored: surfaces take turns on one store and each continues the list; an
   interactive session's entries are there in the next one.
6. vega check names every convention a spec seems to mean but misses, and
   none in the examples.
9. Hot swap: a new module replaces the running one, states keeping their
   values by name, whether a script swaps it or --watch (web, and the TUI on
   a pseudo-terminal) sees its file written again, even at the same size
   within the same second; a module that does not load leaves the app as it
   was.
7. Painting: the bytes the TUI sends, replayed by a small terminal emulator,
   give the very frame the dump shows, while sending only what changed.
8. Web: the GUI surface's screen JSON matches the model after random keys,
   text and row clicks, holds only the rows asked for around the focus, and
   every open page hears of each change. In headless Chromium (when node and
   chromium are there) the page itself takes keys, a click and typed text.
10. Symbols: SVG icons (arcs, compact flags, holes, no viewBox) become
   outlines of the right area, an icon asking for what symbols cannot hold is
   refused by name, damaged files are refused whole, and (when DejaVu Sans is
   there) glyphs keep their exact area and draw within a few levels of
   FreeType's own coverage, and (when there is an OpenGL ES 3.1 device) text
   the GPU composes from an atlas is what the CPU reference draws.
"""
import argparse
import json
import math
import os
import random
import shutil
import subprocess
import sys
import tempfile
import unicodedata
from pathlib import Path

HERE = Path(__file__).resolve().parent
ROOT = HERE.parent


def run(*args, stdin='', env=None):
    return subprocess.run([str(a) for a in args], input=stdin, capture_output=True, text=True, timeout=120,
                          env=env)


def width(text):
    total = 0
    for ch in text:
        if unicodedata.combining(ch) or ch in '‍️':
            continue
        total += 2 if unicodedata.east_asian_width(ch) in 'WF' else 1
    return total


def pictures(text):
    """Control characters as Vega shows them."""
    return ''.join(chr(0x2400 + ord(c)) if ord(c) < 0x20 else '␡' if c == '\x7f' else c for c in text)


class Todo:
    """examples/todo.aup and Vega's reading of it."""

    def __init__(self):
        self.tasks, self.at = [], 0

    def event(self, name, text=None):
        """Returns False when the event fails (a missing item). point takes
        the row as text: a surface focusing it, as a click would."""
        if name == 'point':
            if not 0 <= text < len(self.tasks):
                return False
            self.at = text
            return True
        if name == 'add':
            self.tasks.append({'title': text, 'done': 0, 'urgent': 0})
            self.at = len(self.tasks) - 1
            return True
        last = max(len(self.tasks) - 1, 0)
        if name in ('toggle', 'urgent', 'drop') and not self.tasks:
            return False
        if name == 'up': self.at = max(self.at - 1, 0)
        elif name == 'down': self.at = min(self.at + 1, last)
        elif name == 'toggle': self.tasks[self.at]['done'] = int(not self.tasks[self.at]['done'])
        elif name == 'urgent': self.tasks[self.at]['urgent'] = int(not self.tasks[self.at]['urgent'])
        elif name == 'drop':
            del self.tasks[self.at]
            self.at = min(self.at, max(len(self.tasks) - 1, 0))
        return True

    def left(self):
        """The left field: open tasks of all, a count over the list."""
        return f"{sum(1 for t in self.tasks if not t['done'])} of {len(self.tasks)}"

    @staticmethod
    def badge(task):
        return 'done' if task['done'] else 'urgent' if task['urgent'] else ''

    @staticmethod
    def tone(task):
        return 'muted' if task['done'] else 'danger' if task['urgent'] else 'normal'

    def cli(self):
        lines = ['To do', f'left: {self.left()}', f'tasks_list ({len(self.tasks)})']
        for i, task in enumerate(self.tasks):
            line = ('> ' if i == self.at else '  ') + pictures(task['title'])
            if self.badge(task):
                line += f' [{self.badge(task)}]'
            if self.tone(task) != 'normal':
                line += f' ({self.tone(task)})'
            lines.append(line)
        return lines

    @staticmethod
    def spoken(text):
        text = text.rstrip(''.join(chr(c) for c in range(0x21)))
        return ''.join(' ' if ord(c) < 0x20 else c for c in text)

    def focus(self):
        if not self.tasks:
            return 'tasks_list is empty.'
        task = self.tasks[self.at]
        words = [self.spoken(task['title'])] + ([self.badge(task)] if self.badge(task) else [])
        tone = 'danger, ' if self.tone(task) == 'danger' else ''
        return f'Item {self.at + 1} of {len(self.tasks)}: {tone}' + ', '.join(words) + '.'

    def say(self):
        n = len(self.tasks)
        lines = ['To do.', f'left: {self.left()}.', f'tasks_list, {n} item{"" if n == 1 else "s"}.']
        return lines + ([self.focus()] if n else [])


KEYS = {'up': 'ArrowUp', 'down': 'ArrowDown', 'toggle': 'Space', 'urgent': 'KeyU', 'drop': 'Delete'}
WORDS = ['milk', '우유 사기', 'call 엄마', '日本語', '😀 party', 'café', 'tab\there', 'x' * 60, '', 'a\nb',
         'ok']


def cli_and_say(vega, module, seeds, steps=300):
    compared = failures = 0
    for seed in seeds:
        rng = random.Random(seed)
        model, script, expected_cli, expected_say = Todo(), [], [], []
        for _ in range(steps):
            roll = rng.random()
            if roll < 0.1:
                row = rng.randrange(len(model.tasks) + 2)
                script.append(f'point tasks_list {row}')
                ok, name = model.event('point', row), 'point'
            elif roll < 0.35:
                word = rng.choice(WORDS)
                script.append('text ' + (word.encode().hex() or '-'))
                ok, name = model.event('add', word), 'add'
            else:
                name = rng.choice(list(KEYS) + ['drop'])
                script.append(f'key {KEYS[name]}')
                ok = model.event(name)
            expected_say.append(model.focus() if ok else f'Could not {name}.')
            failures += not ok
            if rng.random() < 0.2:
                script.append('show')
                expected_cli += model.cli()
                expected_say += model.say()
        text = '\n'.join(script) + '\n'
        cli = run(vega, 'cli', module, stdin=text)
        assert cli.returncode == 0 and cli.stdout.splitlines() == expected_cli, \
            (seed, [(a, b) for a, b in zip(cli.stdout.splitlines(), expected_cli) if a != b][:3])
        say = run(vega, 'say', module, stdin=text)
        assert say.returncode == 0 and say.stdout.splitlines() == expected_say, \
            (seed, [(a, b) for a, b in zip(say.stdout.splitlines(), expected_say) if a != b][:3])
        compared += len(expected_cli) + len(expected_say)
    return compared, failures


def stored_surfaces(vega, module, work, seeds, steps=240):
    """One store, several surfaces in turn: each run continues the list where
    the last one left it, and prints or says what the model says."""
    compared = 0
    for seed in seeds:
        rng = random.Random(seed + 500)
        model, store = Todo(), work / f'store-{seed}'
        cuts = sorted(rng.sample(range(1, steps), 6))
        for number, (start, end) in enumerate(zip([0] + cuts, cuts + [steps])):
            surface = ['cli', 'say'][number % 2]
            script, expected = [], []
            for _ in range(start, end):
                roll = rng.random()
                if roll < 0.1:
                    row = rng.randrange(len(model.tasks) + 1)
                    script.append(f'point tasks_list {row}')
                    ok, name = model.event('point', row), 'point'
                elif roll < 0.4:
                    word = rng.choice(WORDS)
                    script.append('text ' + (word.encode().hex() or '-'))
                    ok, name = model.event('add', word), 'add'
                else:
                    name = rng.choice(list(KEYS) + ['drop'])
                    script.append(f'key {KEYS[name]}')
                    ok = model.event(name)
                if surface == 'say':
                    expected.append(model.focus() if ok else f'Could not {name}.')
            script.append('show')
            expected += model.cli() if surface == 'cli' else model.say()
            out = run(vega, surface, module, '--store', store, stdin='\n'.join(script) + '\n')
            assert out.returncode == 0 and out.stdout.splitlines() == expected, \
                (seed, number, [(a, b) for a, b in zip(out.stdout.splitlines(), expected) if a != b][:3])
            compared += len(expected)
        frame = run(vega, 'tui', module, '--store', store, '--dump', '40x12', stdin='show\n').stdout.splitlines()
        assert frame[2].startswith(f'|tasks_list ({len(model.tasks)})'), frame
    return compared


def frames(output, height):
    lines = output.splitlines()
    for start in range(0, len(lines), height + 1):
        frame, cells = lines[start:start + height], lines[start + height]
        assert len(frame) == height and cells.startswith('cells '), lines[start:start + height + 1]
        yield frame, int(cells.split()[1])


def tui(vega, module, seeds, sizes, steps=300):
    """Each frame against the model: which rows show, which one is focused,
    where badges end, and how many cells were evaluated."""
    checked = 0
    for columns, rows in sizes:
        area = rows - 5  # title, field, list header, key bar, input line
        for seed in seeds:
            rng = random.Random(seed * 7 + columns)
            model, script, states, scroll = Todo(), [], [], 0
            for step in range(steps):
                roll = rng.random()
                if roll < 0.12 and step:
                    # A click on a line of the last frame: an item line focuses that item.
                    line = rng.randrange(rows)
                    script.append(f'click {line + 1} 3')
                    if 3 <= line < 3 + area and scroll + line - 3 < len(model.tasks):
                        model.event('point', scroll + line - 3)
                elif roll < 0.4:
                    word = rng.choice(WORDS)
                    script.append('text ' + (word.encode().hex() or '-'))
                    model.event('add', word)
                else:
                    name = rng.choice(list(KEYS))
                    script.append(f'key {KEYS[name]}')
                    model.event(name)
                script.append('show')
                n = len(model.tasks)
                if model.at < scroll: scroll = model.at
                if model.at >= scroll + area: scroll = model.at - area + 1
                if scroll + area > n: scroll = max(n - area, 0)
                states.append(([dict(t) for t in model.tasks], model.at))
            result = run(vega, 'tui', module, '--dump', f'{columns}x{rows}', stdin='\n'.join(script) + '\n')
            assert result.returncode == 0, result.stderr
            first = 0
            for (frame, cells), (tasks, at) in zip(frames(result.stdout, rows), states):
                n = len(tasks)
                assert frame[0] == '|To do' and frame[2].startswith(f'|tasks_list ({n})'), frame[:3]
                if at < first: first = at
                if at >= first + area: first = at - area + 1
                if first + area > n: first = max(n - area, 0)
                shown = frame[3:3 + area]
                visible = tasks[first:first + area]
                for i, line in enumerate(shown):
                    if i >= len(visible):
                        assert line == '|', (seed, line)
                        continue
                    task, focused = visible[i], first + i == at
                    body = (line[1:].split('\t')[0] + '  ')[:max(2, len(line[1:].split('\t')[0]))]  # trailing spaces are trimmed
                    assert line[0] == ('>' if focused else '|') and body.startswith('> ' if focused else '  '), (seed, i, line)
                    label = pictures(task['title'])
                    badge = Todo.badge(task)
                    if badge:  # the badge ends at the last column
                        assert body.endswith(badge) and width(body) == columns, (seed, body, width(body))
                    if width(label) + 2 + (len(badge) + 2 if badge else 0) <= columns:
                        assert body[2:].startswith(label), (seed, body, label)
                    else:
                        assert '…' in body, (seed, body)
                    tone = Todo.tone(task)
                    assert (line.split('\t')[1] if '\t' in line else 'normal') == tone, (seed, line, tone)
                assert cells == 2 + (2 + 3 * len(visible) if n else 0), (seed, cells, len(visible))
                checked += 1
    # A long list costs what its screen shows: 2,000 tasks, 7 visible rows.
    script = ['text ' + f'task {i}'.encode().hex() for i in range(2000)] + ['key ArrowUp'] * 3 + ['show']
    frame, cells = next(frames(run(vega, 'tui', module, '--dump', '40x12', stdin='\n'.join(script) + '\n').stdout, 12))
    assert cells == 2 + 2 + 3 * 7 and frame[9] == '>> task 1996' and frame[3] == '|  task 1990', (cells, frame)
    return checked


TONE_NAMES = ['normal', 'muted', 'accent', 'good', 'warning', 'danger']


def replay(stream, screen):
    """Apply terminal bytes to screen (rows of [text, tone, focus] cells) as a
    terminal would: cursor moves, clearing, colors and reverse video, wide
    characters over two cells, combining marks joining the character before."""
    text, row, col, tone, focus, i = stream.decode(), 0, 0, 0, False, 0
    while i < len(text):
        ch = text[i]
        if ch == '\x1b':
            assert text[i + 1] == '[', repr(text[i:i + 8])
            j = i + 2
            while not '@' <= text[j] <= '~':
                j += 1
            params, final = text[i + 2:j], text[j]
            if final == 'H':
                row, col = (int(n or 1) - 1 for n in (params.split(';') + ['1'])[:2])
            elif final == 'J':
                for line in screen:
                    line[:] = [[' ', 0, False] for _ in line]
            elif final == 'm':
                codes = params.split(';')
                focus = '7' in codes
                tone = next((t for code, t in (('36', 2), ('32', 3), ('33', 4), ('31', 5), ('2', 1)) if code in codes), 0)
            i = j + 1
            continue
        cells = width(ch)
        if not cells:
            back = col - 1
            while back > 0 and screen[row][back][0] == '':
                back -= 1
            screen[row][back][0] += ch
        else:
            screen[row][col] = [ch, tone, focus]
            if cells == 2:
                screen[row][col + 1] = ['', tone, focus]
            col += cells
        i += 1


def shown(screen):
    """A replayed screen in the dump's form."""
    lines = []
    for line in screen:
        focus = any(cell[2] for cell in line)
        text = ''.join(cell[0] for cell in line).rstrip(' ')
        first = next((cell for cell in line if cell[0] not in ('', ' ')), None)
        tone = first[1] if first else 0
        lines.append(('>' if focus else '|') + text + ('\t' + TONE_NAMES[tone] if tone else ''))
    return lines


def painting(vega, module, seeds, sizes, steps=200):
    """Every painted frame equals the dumped one; later frames send only what
    changed. Returns frames compared and the mean bytes of a first and of a
    later frame."""
    compared, first_bytes, later_bytes, later = 0, 0, 0, 0
    for columns, rows in sizes:
        for seed in seeds:
            rng = random.Random(seed * 13 + columns)
            script = []
            for _ in range(steps):
                roll = rng.random()
                if roll < 0.25: script.append('text ' + (rng.choice(WORDS).encode().hex() or '-'))
                elif roll < 0.3: script.append(rng.choice(['type 61', 'enter', 'tab']))
                else: script.append('key ' + rng.choice(list(KEYS.values())))
                script.append('show')
            text = '\n'.join(script) + '\n'
            dumped = [frame for frame, _ in frames(run(vega, 'tui', module, '--dump', f'{columns}x{rows}', stdin=text).stdout,
                                                   rows)]
            painted = subprocess.run([str(vega), 'tui', str(module), '--paint', f'{columns}x{rows}'], input=text.encode(),
                                     capture_output=True, timeout=120)
            assert painted.returncode == 0, painted.stderr
            out, at, screen, n = painted.stdout, 0, [[[' ', 0, False] for _ in range(columns)] for _ in range(rows)], 0
            while at < len(out):
                end = out.index(b'\n', at)
                size = int(out[at:end].split()[1])
                replay(out[end + 1:end + 1 + size], screen)
                assert shown(screen) == dumped[n], (seed, n, shown(screen), dumped[n])
                if n: later_bytes, later = later_bytes + size, later + 1
                else: first_bytes += size
                at, n = end + 2 + size, n + 1
            assert n == len(dumped), (n, len(dumped))
            compared += n
    first_mean = first_bytes // (len(sizes) * len(seeds))
    later_mean = later_bytes // later
    assert later_mean * 3 < first_mean, (first_mean, later_mean)
    return compared, first_mean, later_mean


def web(vega, module, work, seeds, steps=150, visible=4):
    """The web surface against the model: POST keys, text and row clicks, then
    the screen JSON's title, field, rows, focus and the window of items."""
    import http.client
    import signal
    import threading
    compared = 0
    for seed in seeds:
        store = work / f'web-{seed}'
        process = subprocess.Popen([str(vega), 'web', str(module), '--port', '0', '--store', str(store)],
                                   stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        port = json.loads(process.stdout.readline())['port']
        connection = http.client.HTTPConnection('127.0.0.1', port, timeout=10)

        def call(method, path, body=None):
            connection.request(method, path, body.encode() if isinstance(body, str) else body)
            response = connection.getresponse()
            return response.status, response.read()

        heard = []
        stream = http.client.HTTPConnection('127.0.0.1', port, timeout=10)
        stream.request('GET', '/events')
        events = stream.getresponse()
        assert events.getheader('Content-Type') == 'text/event-stream'
        listener = threading.Thread(target=lambda: [heard.append(line) for line in iter(events.readline, b'')
                                                    if line.startswith(b'data:')], daemon=True)
        listener.start()
        status, page = call('GET', '/')
        assert status == 200 and b'EventSource' in page and b"role:'listbox'" in page, page[:80]
        assert call('GET', '/nowhere')[0] == 404
        rng, model, first, part = random.Random(seed + 900), Todo(), 0, None
        for _ in range(steps):
            roll = rng.random()
            if roll < 0.3:
                word = rng.choice(WORDS)
                status, answer = call('POST', '/text', word)
                model.event('add', word)
            elif roll < 0.45 and part is not None:
                row = rng.randrange(len(model.tasks) + 1)
                status, answer = call('POST', '/point', f'{part} {row}')
                assert json.loads(answer)['ok'] == model.event('point', row), (seed, row)
            else:
                name = rng.choice(list(KEYS))
                status, answer = call('POST', '/key', KEYS[name])
                assert json.loads(answer)['ok'] == model.event(name), (seed, name)
            assert status == 200
            status, body = call('GET', f'/screen?rows={visible}&first={first}')
            screen = json.loads(body)
            tasks, n = model.tasks, len(model.tasks)
            (listed,) = screen['parts']
            part = listed['part']
            if model.at < first: first = model.at
            if model.at >= first + visible: first = model.at - visible + 1
            if first + visible > n: first = max(n - visible, 0)
            assert screen['title'] == 'To do' and screen['fields'] == [{'name': 'left', 'text': model.left()}], screen
            assert (listed['rows'], listed['focus'], listed['first']) == (n, model.at if n else None, first), (seed, listed)
            window = tasks[first:first + visible]
            assert [(item['row'], item['label'], item['badge'], item['tone']) for item in listed['items']] == \
                [(first + i, task['title'], Todo.badge(task), Todo.tone(task)) for i, task in enumerate(window)], seed
            assert screen['prompt'] == 'add' and listed['pointable'] and listed['kind'] == 'list'
            compared += 1
        process.send_signal(signal.SIGTERM)
        assert process.wait(timeout=10) == 0, process.stderr.read()
        listener.join(timeout=5)
        assert len(heard) > steps // 2, len(heard)  # a change each time, more or less merged
        again = run(vega, 'cli', module, '--store', store, stdin='show\n').stdout.splitlines()
        assert again == model.cli(), (again, model.cli())
    return compared


class WebSurface:
    """vega web on a free port; stops with SIGTERM."""

    def __init__(self, vega, module, *args):
        self.process = subprocess.Popen([str(vega), 'web', str(module), '--port', '0', *map(str, args)],
                                        stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        self.port = json.loads(self.process.stdout.readline())['port']

    def call(self, method, path, body=None):
        import http.client
        connection = http.client.HTTPConnection('127.0.0.1', self.port, timeout=10)
        try:
            connection.request(method, path, body.encode() if isinstance(body, str) else body)
            response = connection.getresponse()
            return response.status, response.read()
        finally:
            connection.close()

    def stop(self):
        import signal
        self.process.send_signal(signal.SIGTERM)
        assert self.process.wait(timeout=10) == 0, self.process.stderr.read()


def browser(vega, module, work):
    """The page in headless Chromium: keys, a click on a row, typed text."""
    import shutil
    if not shutil.which('node') or not shutil.which('chromium'):
        return 'skipped'
    store = work / 'browser-store'
    assert run(vega, 'cli', module, '--store', store, stdin='text 61\ntext 62\ntext 63\n').returncode == 0
    surface = WebSurface(vega, module, '--store', store)
    try:
        result = run('node', HERE / 'browser.mjs', f'http://127.0.0.1:{surface.port}/')
    finally:
        surface.stop()
    outcome = json.loads(result.stdout)
    assert result.returncode == 0 and outcome['ok'], outcome
    after = run(vega, 'cli', module, '--store', store, stdin='show\n').stdout.splitlines()
    assert after == ['To do', 'left: 3 of 4', 'tasks_list (4)', '  a [done] (muted)', '  b', '  c', '> 브라우저'], after
    return len(outcome['steps'])


def split(vega, module, work, seeds, steps=200):
    """examples/today.aup: two lists filtered from one list share one focus.
    The CLI shows each list's items in order with the focus in whichever
    list holds it; point takes a row of either list; the web surface gives
    the other list no focus."""
    compared = 0
    for seed in seeds:
        rng, tasks, at, script, expected = random.Random(seed + 700), [], 0, [], []
        for _ in range(steps):
            roll = rng.random()
            opened = [i for i, t in enumerate(tasks) if not t['done']]
            closed = [i for i, t in enumerate(tasks) if t['done']]
            if roll < 0.3:
                word = rng.choice(WORDS)
                script.append('text ' + (word.encode().hex() or '-'))
                tasks.append({'title': word, 'done': 0})
                at = len(tasks) - 1
            elif roll < 0.5:
                name, rows = rng.choice([('open', opened), ('done', closed)])
                row = rng.randrange(len(rows) + 1)
                script.append(f'point {name} {row}')
                if row < len(rows): at = rows[row]
            else:
                key = rng.choice(['ArrowUp', 'ArrowDown', 'Space'])
                script.append(f'key {key}')
                if key == 'ArrowUp': at = max(at - 1, 0)
                elif key == 'ArrowDown': at = min(at + 1, max(len(tasks) - 1, 0))
                elif tasks: tasks[at]['done'] = int(not tasks[at]['done'])
            if rng.random() < 0.3:
                script.append('show')
                opened = [i for i, t in enumerate(tasks) if not t['done']]
                closed = [i for i, t in enumerate(tasks) if t['done']]
                expected += ['Today', f'left: {len(opened)} open', f'open ({len(opened)})']
                expected += [('> ' if i == at else '  ') + pictures(tasks[i]['title']) for i in opened]
                expected += [f'done ({len(closed)})']
                expected += [('> ' if i == at else '  ') + pictures(tasks[i]['title']) + ' (muted)' for i in closed]
        out = run(vega, 'cli', module, stdin='\n'.join(script) + '\n')
        assert out.returncode == 0 and out.stdout.splitlines() == expected, \
            (seed, [(a, b) for a, b in zip(out.stdout.splitlines(), expected) if a != b][:3])
        compared += len(expected)
    surface = WebSurface(vega, module)
    try:
        for word in ('a', 'b', 'c'): surface.call('POST', '/text', word)
        surface.call('POST', '/key', 'Space')  # c is done: the focus moves to the done list
        parts = json.loads(surface.call('GET', '/screen?rows=5')[1])['parts']
    finally:
        surface.stop()
    assert [(p['name'], p['rows'], p['focus']) for p in parts] == [('open', 2, None), ('done', 1, 0)], parts
    return compared


def hot_swap(vega, aup, work):
    """Swap a module under a running app: by script, and by --watch in the
    web surface when the file is written again (atomically, as aup watch
    writes it). States keep their values by name; a broken module is refused."""
    import time
    env = dict(os.environ, AUP_PATH=str(ROOT / 'lib'))
    source = (ROOT / 'examples/todo.aup').read_text()
    changed = source.replace('view title = "To do"', 'view title = "Things"') + \
        'view done_count = count(t in tasks where t.done)\n'
    modules = []
    # again differs from after in one letter: a module of the same size, written within the same second.
    for name, text in (('before', source), ('after', changed), ('again', changed.replace('"Things"', '"Thingz"'))):
        (work / f'{name}.aup').write_text(text)
        assert run(aup, 'build', work / f'{name}.aup', '-o', work / f'{name}.pmod', env=env).returncode == 0
        modules.append(work / f'{name}.pmod')
    script = f'text 61\ntext 62\nkey Space\nswap {modules[1]}\nkey ArrowUp\nshow\n'
    out = run(vega, 'cli', modules[0], stdin=script).stdout.splitlines()
    assert out == ['Things', 'left: 1 of 2', 'tasks_list (2)', '> a', '  b [done] (muted)', 'done_count: 1'], out
    # --watch: the web surface takes the new module and tells every page.
    live = work / 'live.pmod'
    shutil.copy(modules[0], live)
    surface = WebSurface(vega, live, '--watch')
    import http.client
    import threading
    heard = []
    stream = http.client.HTTPConnection('127.0.0.1', surface.port, timeout=10)
    stream.request('GET', '/events')
    events = stream.getresponse()
    threading.Thread(target=lambda: [heard.append(line) for line in iter(events.readline, b'') if line.startswith(b'data:')],
                     daemon=True).start()
    def replace(module, title):
        """Write module over the watched file as aup does, and wait for the page to show title."""
        shutil.copy(module, work / 'live.tmp')
        os.replace(work / 'live.tmp', live)
        for _ in range(50):
            screen = json.loads(surface.call('GET', '/screen')[1])
            if screen['title'] == title: return screen
            time.sleep(0.05)
        raise AssertionError(f'never shown: {title}: {screen}')

    try:
        for word in ('a', 'b'): surface.call('POST', '/text', word)
        surface.call('POST', '/key', 'Space')
        time.sleep(0.3)
        before = len(heard)
        screen = replace(modules[1], 'Things')
        assert {'name': 'done_count', 'text': '1'} in screen['fields'], screen
        assert [item['label'] for item in screen['parts'][0]['items']] == ['a', 'b'], screen
        time.sleep(0.2)
        assert len(heard) > before, 'the page hears of the new module'
        assert modules[2].stat().st_size == modules[1].stat().st_size
        replace(modules[2], 'Thingz')
        (work / 'live.tmp').write_bytes(b'not a module')
        os.replace(work / 'live.tmp', live)
        time.sleep(0.6)
        assert json.loads(surface.call('GET', '/screen')[1])['title'] == 'Thingz'  # the broken one is refused
    finally:
        surface.stop()
    shutil.copy(modules[0], work / 'tui.pmod')
    interactive(vega, work / 'tui.pmod', replace=modules[1])
    return len(out)


def timing(vega, module):
    """examples/stopwatch.aup: time is an input. A script sets the time events
    see and ticks the timer; the terminal and the web page tick it on the
    clock, and every page hears of each tick."""
    import fcntl, pty, select, struct, termios, time
    script = ('time 1000\nkey Space\ntime 2500\ntick tick\nshow\ntime 63400\ntick tick\nkey KeyL\n'
              'time 70000\nkey Space\ntick tick\nshow\ntime 71000\nkey KeyR\nshow\n')
    out = run(vega, 'cli', module, stdin=script).stdout.splitlines()
    assert out == ['Stopwatch', 'time: 0:01.5', 'status: running', 'laps_list (0)',
                   'Stopwatch', 'time: 1:09.0', 'status: stopped', 'laps_list (1)', '> 1:02.4 (accent)',
                   'Stopwatch', 'time: 0:00.0', 'status: stopped', 'laps_list (1)', '> 1:02.4 (accent)'], out
    # The terminal, on the clock: start it, and a second and more later it shows that.
    pid, fd = pty.fork()
    if pid == 0:
        os.execv(str(vega), [str(vega), 'tui', str(module)])
    fcntl.ioctl(fd, termios.TIOCSWINSZ, struct.pack('HHHH', 8, 30, 0, 0))
    os.kill(pid, 28)
    screen = b''

    def read_for(seconds):
        nonlocal screen
        end = time.time() + seconds
        while time.time() < end:
            if select.select([fd], [], [], 0.05)[0]:
                try:
                    screen += os.read(fd, 65536)
                except OSError:
                    break

    read_for(0.3)
    os.write(fd, b' ')
    read_for(1.4)
    os.write(fd, b'\x03')
    read_for(0.3)
    _, status = os.waitpid(pid, 0)
    os.close(fd)
    assert os.WIFEXITED(status) and os.WEXITSTATUS(status) == 0, status
    grid = [[[' ', 0, False] for _ in range(30)] for _ in range(8)]
    replay(screen, grid)
    final = '\n'.join(shown(grid))
    import re
    seconds = float(re.search(r'time\s+0:(\d\d\.\d)', final).group(1))
    assert 1.2 <= seconds <= 2.5 and 'running' in final, final
    # The web page: every tick is news to every open page.
    surface = WebSurface(vega, module)
    try:
        import http.client
        stream = http.client.HTTPConnection('127.0.0.1', surface.port, timeout=10)
        stream.request('GET', '/events')
        events = stream.getresponse()
        events.readline(), events.readline()
        surface.call('POST', '/key', 'Space')
        heard = 0
        began = time.time()
        while time.time() - began < 1.0:
            if events.readline().startswith(b'data:'): heard += 1
        page = json.loads(surface.call('GET', '/screen')[1])
        field = next(f['text'] for f in page['fields'] if f['name'] == 'time')
        assert heard >= 6 and float(field.split(':')[1]) >= 0.8, (heard, field)
        stream.close()
    finally:
        surface.stop()
    return len(out), heard


def hosts(vega, serve, module, work):
    """examples/board.aup, one app and one store for people and programs: the
    CLI adds and moves cards, pure-serve serves the same store as a JSON API
    (a program moves one and adds another), and the CLI then shows what the
    program did, its focus still on the card it was on."""
    import http.client
    store = work / 'board-store'
    script = 'time 1000\ntext ' + 'write docs'.encode().hex() + '\ntext ' + 'ship it'.encode().hex() + '\nkey ArrowRight\nshow\n'
    before = run(vega, 'cli', module, '--store', store, stdin=script).stdout.splitlines()
    assert before[-3:] == ['cards_list (2)', '> ship it [doing] (accent)', '  write docs [to do]'], before
    server = subprocess.Popen([str(serve), '--module', str(module), '--store', str(store), '--port', '0'],
                              stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    try:
        port = json.loads(server.stdout.readline())['port']

        def call(method, path, body=None):
            connection = http.client.HTTPConnection('127.0.0.1', port, timeout=10)
            headers = {'Content-Type': 'application/json'} if body else {}
            connection.request(method, path, body, headers)
            response = connection.getresponse()
            answer = response.status, response.read()
            connection.close()
            return answer

        assert call('GET', '/views/counts') == (200, b'1 to do, 1 doing, 0 done')
        assert call('POST', '/inputs/post', '{"title": "write docs", "lane": 2}') == (200, b'write docs')
        assert call('POST', '/inputs/post', '{"title": "from api", "lane": 1}') == (200, b'from api')
        rows = json.loads(call('GET', '/views/cards_list')[1])['items']
        assert [(r['label'], r['badge']) for r in rows] == [('from api', 'doing'), ('ship it', 'doing'),
                                                            ('write docs', 'done')], rows
    finally:
        import signal
        server.send_signal(signal.SIGTERM)
        assert server.wait(timeout=10) == 0, server.stderr.read()
    after = run(vega, 'cli', module, '--store', store, stdin='show\n').stdout.splitlines()
    assert after == ['Board', 'counts: 0 to do, 2 doing, 1 done', 'cards_list (3)', '  from api [doing] (accent)',
                     '> ship it [doing] (accent)', '  write docs [done] (muted)'], after
    return len(rows)


def scores(vega, module):
    joins = ['ann', '범수', 'Zoë']
    script = [f'text {name.encode().hex()}' for name in joins]
    script += ['key ArrowUp', 'key KeyW', 'key KeyW', 'key KeyW', 'key ArrowUp', 'key KeyL', 'show']
    out = run(vega, 'cli', module, stdin='\n'.join(script) + '\n').stdout.splitlines()
    assert out == ['Scores', 'board (3)',
                   '  name  score  rank',
                   '> ann   -1     - (danger)',
                   '  범수  3      gold (good)',
                   '  Zoë   0      -'], out
    tui = run(vega, 'tui', module, '--dump', '30x8', stdin='\n'.join(script) + '\n').stdout.splitlines()
    assert tui[1:5] == ['|board (3)', '|  name  score  rank\tmuted', '>> ann   -1     -\tdanger',
                        '|  범수  3      gold\tgood'], tui
    say = run(vega, 'say', module, stdin='show\n' + '\n'.join(script) + '\n').stdout.splitlines()
    assert 'Item 1 of 3: danger, name ann, score -1, rank -.' in say, say
    # The web surface: a table's columns and cells in order, with tones.
    surface = WebSurface(vega, module)
    try:
        for line in script[:-1]:
            command, argument = line.split()
            if command == 'text': surface.call('POST', '/text', bytes.fromhex(argument))
            else: surface.call('POST', '/key', argument)
        board = json.loads(surface.call('GET', '/screen?rows=10')[1])['parts'][0]
    finally:
        surface.stop()
    assert board['kind'] == 'table' and board['columns'] == ['name', 'score', 'rank'] and board['focus'] == 0, board
    assert [(item['cells'], item['tone']) for item in board['items']] == [
        (['ann', '-1', '-'], 'danger'), (['범수', '3', 'gold'], 'good'), (['Zoë', '0', '-'], 'normal')], board
    return len(out)


def interactive(vega, module, store=None, replace=None):
    """The terminal surface on a real pseudo-terminal: typed text commits
    with Enter, arrow keys and letters reach the app after Tab, Ctrl-C leaves
    and restores the terminal. With replace, it runs with --watch and replace
    is then written over module: the terminal shows it, with the same tasks."""
    import fcntl, pty, select, struct, termios, time
    pid, fd = pty.fork()
    if pid == 0:
        os.execv(str(vega), [str(vega), 'tui', str(module)] + (['--store', str(store)] if store else []) +
                 (['--watch'] if replace else []))
    fcntl.ioctl(fd, termios.TIOCSWINSZ, struct.pack('HHHH', 10, 40, 0, 0))
    os.kill(pid, 28)  # SIGWINCH: take the size

    def read_for(seconds):
        data, end = b'', time.time() + seconds
        while time.time() < end:
            ready, _, _ = select.select([fd], [], [], 0.05)
            if ready:
                try:
                    data += os.read(fd, 65536)
                except OSError:
                    break
        return data

    screen = read_for(0.3)
    # Then a click on line 5 (béton's row): a mouse report, press and release.
    for keys in (b'milk\r', 'b\u00e9ton\r'.encode(), b'\t', b'\x1b[A', b' ', b'u', b'\x1b[<0;3;5M\x1b[<0;3;5m'):
        os.write(fd, keys)
        screen += read_for(0.2)
    if replace:
        shutil.copy(replace, module.with_suffix('.tmp'))
        os.replace(module.with_suffix('.tmp'), module)
        screen += read_for(0.6)
    os.write(fd, b'\x03')
    screen += read_for(0.3)
    _, status = os.waitpid(pid, 0)
    os.close(fd)
    text = screen.decode(errors='replace')
    assert os.WIFEXITED(status) and os.WEXITSTATUS(status) == 0, status
    assert '\x1b[?1049h' in text and text.rstrip().endswith('\x1b[?1049l'), text[-80:]
    # What the terminal ended up showing, from the bytes it was sent.
    grid = [[[' ', 0, False] for _ in range(40)] for _ in range(10)]
    replay(screen, grid)
    final = shown(grid)
    if replace:  # the new title and field, the same tasks, focus and done mark
        assert final[:3] == ['|Things', '|left  1 of 2\tmuted', '|done_count  1\tmuted'], final
        assert final[4].startswith('|  milk') and 'done' in final[4] and final[5].startswith('>> béton'), final
    else:
        assert 'milk' in '\n'.join(final) and '(2)' in final[2] and 'done' in final[3], final
        assert final[4].startswith('>> béton') and final[3].startswith('|  milk'), final  # the click moved the focus
    assert '\x1b[?1000h' in text and '\x1b[?1000l' in text, 'mouse reports on, then off'
    if store:  # what was typed is still there in the next session
        again = run(vega, 'cli', module, '--store', store, stdin='show\n').stdout.splitlines()
        assert again == ['To do', 'left: 1 of 2', 'tasks_list (2)', '  milk [done] (muted)', '> béton'], again
    return 1


BROKEN_SPEC = """use vega
record Item {
  name: text
  size = 0
}
state items: list of Item
state at: index of items
input add = text
input note = text
input up = key ArrowUp
on add { items.append(Item { name: add }) }
on note { items.append(Item { name: note }) }
on up.down { at = at - 1 }
view title = 3
view items_list = each item in items {
  label = item.name
  tone = "red"
  badge = item.size
  size = item.size
}
view sizes = each item in items {
  label = item.size
}
view empty = each item in items {
  tone = vega.muted
}
view missing_focus = 1
view items_list_focus = "0"
"""


def conventions(vega, aup, work, modules):
    """Every convention the broken spec misses, and none in the examples."""
    env = dict(os.environ, AUP_PATH=str(ROOT / 'lib'))
    (work / 'broken.aup').write_text(BROKEN_SPEC)
    built = run(aup, 'build', work / 'broken.aup', '-o', work / 'broken.pmod', env=env)
    assert built.returncode == 0, built.stderr
    result = run(vega, 'check', work / 'broken.pmod')
    found = [line.split(': ', 1)[1] for line in result.stdout.splitlines()]
    assert result.returncode == 1 and found == [
        'title: a title is text; this one shows as a field',
        'items_list.tone: a tone is a number (vega.normal ... vega.danger); the list ignores it',
        "items_list.badge: a list's badge is text; this one is not shown",
        'items_list.size: a list shows label, badge, detail and tone; this column is not shown',
        "sizes.label: a list's label is text; sizes shows as a table",
        'empty: a table with no column to show',
        'missing_focus: names no list or table missing; it shows as a field',
        'items_list_focus: the focused row is a number; items_list shows no focus',
        'note: only the first text input (add) has a place to type into'], result.stdout
    for module in modules.values():
        clean = run(vega, 'check', module)
        assert clean.returncode == 0 and not clean.stdout, clean.stdout
    return len(found)


def robustness(vega, aup, work, rounds):
    """Every aup example, every surface, random keys and text: never a crash."""
    examples = sorted((ROOT.parent / 'aup' / 'examples').glob('*.aup')) + sorted((ROOT / 'examples').glob('*.aup'))
    keys = ['ArrowUp', 'ArrowDown', 'ArrowLeft', 'ArrowRight', 'Space', 'Enter', 'Delete', 'Backspace', 'Home',
            'End', 'KeyD', 'KeyS', 'KeyU', 'KeyW', 'KeyL', 'KeyM']
    env = dict(os.environ, AUP_PATH=str(ROOT / 'lib'))
    runs = 0
    for path in examples:
        module = work / (path.stem + '.pmod')
        built = run(aup, 'build', path, '-o', module, env=env)
        assert built.returncode == 0, (path, built.stderr)
        assert run(vega, 'check', module).returncode in (0, 1), path
        rng = random.Random(path.stem)
        for _ in range(rounds):
            script = []
            for _ in range(60):
                roll = rng.random()
                if roll < 0.2: script.append('text ' + rng.choice(WORDS).encode().hex())
                elif roll < 0.3: script.append('show')
                elif roll < 0.35: script.append('frame 3')
                elif roll < 0.4: script.append(rng.choice(['type 61', 'enter', 'tab']))
                elif roll < 0.45: script.append(f'click {rng.randrange(1, 30)} {rng.randrange(1, 90)}')
                else: script.append('key ' + rng.choice(keys))
            text = '\n'.join(script) + '\nshow\n'
            size = rng.choice(['80x24', '12x5', '1x1', '200x3'])
            for surface in (['cli'], ['say'], ['tui', '--dump', size], ['tui', '--paint', size]):
                result = run(vega, surface[0], module, *surface[1:], stdin=text)
                assert result.returncode == 0, (path, surface, result.stderr[-400:])
                runs += 1
        # The web surface under random posts: every answer well formed, and a clean stop.
        surface = WebSurface(vega, module)
        try:
            for _ in range(40):
                roll = rng.random()
                if roll < 0.3: surface.call('POST', '/text', rng.choice(WORDS))
                elif roll < 0.4: surface.call('POST', '/point', f'{rng.randrange(4)} {rng.randrange(4)}')
                else: surface.call('POST', '/key', rng.choice(keys))
                status, body = surface.call('GET', f'/screen?rows={rng.randrange(0, 30)}&first={rng.randrange(9)},1')
                assert status == 200 and isinstance(json.loads(body)['parts'], list), (path, body[:200])
        finally:
            surface.stop()
        runs += 1
    return len(examples), runs


def symbols(tool, work):
    """Build, read back and damage symbol files (docs/design/002-symbol-format.md)."""
    icons = ROOT / 'tests' / 'symbols'
    out = work / 'icons.vsym'
    built = run(tool, 'build', '--svg', f'0xE002={icons / "rounded.svg"}', '--svg', f'0xE000={icons / "circle.svg"}',
                '--svg', f'0xE001={icons / "frame.svg"}', '-o', out)
    assert built.returncode == 0, built.stderr
    info = json.loads(run(tool, 'info', out).stdout)
    units = info['units']
    square = (units / 16) ** 2  # an icon pixel, in square units
    expected = {0xE000: math.pi * 49, 0xE001: 196 - 64, 0xE002: 196 - 16 + 4 * math.pi}
    assert [s['code'] for s in info['symbols']] == sorted(expected), info
    for symbol in info['symbols']:
        area = abs(symbol['area']) / square
        assert abs(area - expected[symbol['code']]) < 2e-3 * expected[symbol['code']], (symbol, expected)
        assert symbol['bounds'] == [units // 16, units // 16, units * 15 // 16, units * 15 // 16], symbol
        assert symbol['advance'] == units, symbol
    refused = run(tool, 'build', '--svg', f'0xE000={icons / "turned.svg"}', '-o', work / 'turned.vsym')
    assert refused.returncode != 0 and 'turned.svg' in refused.stderr and 'transform' in refused.stderr, refused.stderr
    twice = run(tool, 'build', '--svg', f'0xE000={icons / "circle.svg"}', '--svg', f'0xE000={icons / "frame.svg"}',
                '-o', work / 'twice.vsym')
    assert twice.returncode != 0 and 'twice' in twice.stderr, twice.stderr

    picture = work / 'circle.pgm'
    assert run(tool, 'render', out, '0xE000', 32, picture).returncode == 0
    header, pixels = picture.read_bytes().split(b'255\n', 1)
    w, h = map(int, header.split()[1:3])
    assert len(pixels) == w * h and abs(sum(pixels) / 255 - math.pi * 49 * 4) < 2, (w, h, sum(pixels) / 255)
    assert run(tool, 'render', out, '0x41', 32, picture).returncode != 0  # no such symbol

    good = out.read_bytes()
    count = int.from_bytes(good[12:16], 'little')
    records = 28

    def damaged(name, data):
        path = work / f'{name}.vsym'
        path.write_bytes(bytes(data))
        refused = run(tool, 'info', path)
        assert refused.returncode != 0 and refused.stdout == '', (name, refused.stdout)
        return refused.stderr.strip()

    why = [damaged('short', good[:-1]), damaged('magic', b'VEGASYM9' + good[8:])]
    swapped = bytearray(good)
    swapped[records:records + 24], swapped[records + 24:records + 48] = good[records + 24:records + 48], good[records:records + 24]
    why.append(damaged('order', swapped))
    beyond = bytearray(good)
    beyond[records + 8:records + 12] = (1 << 20).to_bytes(4, 'little')
    why.append(damaged('beyond', beyond))
    flagged = bytearray(good)
    flagged[records + 22] = 1
    why.append(damaged('flags', flagged))
    counted = bytearray(good)
    counted[12:16] = (count + 1).to_bytes(4, 'little')
    why.append(damaged('count', counted))
    # A symbol's first point starts a contour on the curve, and its last is
    # on it, so an off point's neighbours never leave the symbol.
    points = records + 24 * count
    first, length = (int.from_bytes(good[records + k:records + k + 4], 'little') for k in (4, 8))
    unmoved = bytearray(good)
    unmoved[points + 4 * first + 2] &= 0xFE
    why.append(damaged('unmoved', unmoved))
    open_end = bytearray(good)
    open_end[points + 4 * (first + length - 1)] |= 1
    why.append(damaged('open', open_end))
    assert len(set(why)) == len(why), why

    report = {'icons': len(info['symbols'])}
    font = Path('/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf')
    if font.exists():
        glyphs = work / 'ascii.vsym'
        assert run(tool, 'build', '--font', font, '--codes', '0x20-0x7e', '-o', glyphs).returncode == 0
        lines = run(tool, 'compare', font, glyphs, '--sizes', '12,16,32').stdout.splitlines()
        for line in lines[1:]:
            size = json.loads(line)
            assert size['glyphs'] == 94 and size['mean_difference'] < 3 and size['within_16'] > 0.99, size
        report['glyph_sizes'] = len(lines) - 1
        # Text composed by the GPU from the atlas is what vega_symbol_raster
        # draws at the same pen positions (when there is an OpenGL ES 3.1 device).
        drawn = run(tool, 'gpu', glyphs, '--sizes', '12,32', '--frames', 1)
        if drawn.returncode == 0:
            for line in drawn.stdout.splitlines()[1:]:
                size = json.loads(line)
                assert size['symbols'] == 95 and size['worst'] <= 1 and size['page_glyphs'] > 1000, size
            report['gpu_sizes'] = len(drawn.stdout.splitlines()) - 1
        else:
            assert 'EGL' in drawn.stderr or 'OpenGL' in drawn.stderr, drawn.stderr
        try:
            from fontTools.pens.areaPen import AreaPen
            from fontTools.ttLib import TTFont
        except ImportError:
            return report
        face = TTFont(font)
        outlines, cmap, metrics = face.getGlyphSet(), face.getBestCmap(), face['hmtx']
        shown = json.loads(run(tool, 'info', glyphs).stdout)
        assert shown['units'] == face['head'].unitsPerEm, shown['units']  # a TrueType font's points stay whole
        for symbol in shown['symbols']:
            pen = AreaPen()
            outlines[cmap[symbol['code']]].draw(pen)
            assert abs(abs(pen.value) - abs(symbol['area'])) < 1, (chr(symbol['code']), pen.value, symbol)
            assert symbol['advance'] == metrics[cmap[symbol['code']]][0], (chr(symbol['code']), symbol)
        report['exact_glyphs'] = len(shown['symbols'])
    return report


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument('--vega', type=Path, required=True)
    parser.add_argument('--aup', type=Path, required=True)
    parser.add_argument('--serve', type=Path, required=True)
    parser.add_argument('--symbols', type=Path)
    parser.add_argument('--seeds', type=int, default=8)
    parser.add_argument('--rounds', type=int, default=3)
    args = parser.parse_args()
    vega, aup = args.vega.resolve(), args.aup.resolve()
    report = {}
    with tempfile.TemporaryDirectory(prefix='vega-check-') as directory:
        work = Path(directory)
        env = dict(os.environ, AUP_PATH=str(ROOT / 'lib'))
        modules = {}
        for name in ('todo', 'scores', 'today', 'stopwatch', 'board'):
            modules[name] = work / f'{name}.pmod'
            built = run(aup, 'build', ROOT / 'examples' / f'{name}.aup', '-o', modules[name], env=env)
            assert built.returncode == 0, built.stderr
        report['cli_and_say_lines'], report['failed_events_spoken'] = \
            cli_and_say(vega, modules['todo'], range(args.seeds))
        report['tui_frames'] = tui(vega, modules['todo'], range(args.seeds), [(40, 12), (24, 9), (80, 30), (16, 6)])
        report['table_lines'] = scores(vega, modules['scores'])
        report['timed_lines'], report['ticks_heard'] = timing(vega, modules['stopwatch'])
        report['board_rows_across_hosts'] = hosts(vega, args.serve.resolve(), modules['board'], work)
        report['hot_swap_lines'] = hot_swap(vega, aup, work)
        report['split_list_lines'] = split(vega, modules['today'], work, range(args.seeds))
        report['painted_frames'], report['first_paint_bytes'], report['later_paint_bytes'] = \
            painting(vega, modules['todo'], range(args.seeds), [(40, 12), (24, 9), (80, 30)])
        report['web_screens'] = web(vega, modules['todo'], work, range(args.seeds))
        report['browser_steps'] = browser(vega, modules['todo'], work)
        report['interactive_sessions'] = interactive(vega, modules['todo']) + \
            interactive(vega, modules['todo'], work / 'interactive-store')
        report['stored_surface_lines'] = stored_surfaces(vega, modules['todo'], work, range(args.seeds))
        report['convention_findings'] = conventions(vega, aup, work, modules)
        report['examples'], report['robustness_runs'] = robustness(vega, aup, work, args.rounds)
        if args.symbols:
            report['symbols'] = symbols(args.symbols.resolve(), work)
    print(json.dumps(report))


if __name__ == '__main__':
    sys.exit(main())