+ is_deeply(
+ $index->ranges({ pagesize=>10, context=>3 }),
+ # shorten 'kuap' to 'ku' because lookbehind is 'kp...'
+ # 'lguq' matches 'lg', but may only backtrack to 'lgu'
+ [qw(-kt ku-lgt lgu-)],
+ 'lookbehind'
+ );
+ is_deeply(
+ $index->ranges({ pagesize=>10, context=>4 }),
+ [qw(-kt ku-lf lg-)],
+ 'maximal lookahead'
+ );
+ is_deeply(
+ $index->ranges({ pagesize=>10, context=>5 }),
+ # after forwarding 'kuap' to 'lc'
+ # disallow backtracking of 'lguq' to 'lc' to prevent qw[-k l-]
+ # so only lookahead (to 'lkq') remains
+ [qw(-k l-lj lk-)],
+ 'lookbehind forbidden'
+ );
+ is_deeply(
+ $index->ranges({ pagesize=>10, context=>9 }),
+ # allow a single (10-9) entry (l-lf = lc) to remain
+ [qw(-k l-lf lg-)],
+ 'lookbehind penalty'
+ );
+ is_deeply(
+ $index->ranges({ pagesize=>10, context=>10 }),
+ # allow the last page to go back upto 'lc', replacing the 2nd page
+ [qw(-k l-)],
+ 'full overlap'
+ );
+};
+
+subtest 'distribution' => sub {
+ plan tests => 2;
+ my $index = List::Index->new([qw(
+ gnihka gniub go gsearnrqns gtdvcxyt gw gwoufolwcvmtueyg gysgphci h habkdgifjfxoh
+ hbbvjf hbqleexnqts hccg hd hdoeqwdmgqwaoya hfbegicieuxz hfm hj hkoysmws hmylu
+ hnvtvpievbdlkrmb hs hvdvcqn hvn hyrybeur iaiaab ib ibavqyar idfniqvxpohbk idh
+ )]) or return;
+ is_deeply(
+ $index->ranges({ pagesize=>10, context=>8 }),
+ [qw(-g h i-)],
+ 'large context'
+ );
+ is_deeply(
+ $index->ranges({ pagesize=>10, context=>7 }),
+ # after 2nd page is enlarged by lookbehind to 'h', limit subsequent lookahead
+ # to prevent the page from getting too large (17 entries if forwarded to 'i')
+ [qw(-g h-hm hn-)],
+ 'lookahead penalty'
+ );
+ # page #14 [gn-g] (8): gnihka gniub go gsearnrqns gtdvcxyt gwawkvmueovdjtfj gwoufolwcvmtueyg gysgphci
+ # page #15 [h] (17): h habkdgifjfxoh hbbvjf hbqleexnqts hccgszftbaymfu hdaqzkow hdoeqwdmgqwaoya hfbegicieu hfmlpzzioqjbthz hj hkoysmws hmylu hnvtvpievbdlkrmb hsodfpkatk hvdvcqn hvn hyrybeurqtevjfmi
+ # page #16 [i-ie] (5): i iaab ibiavqyar idfniqvxpohbk idh
+};