+ my @data = ('aa'..'zz', 1..202);
+ my $index = List::Index->new or return;
+
+ is_deeply(
+ $index->ranges(\@data),
+ [qw(
+ -.. ..-...
+ ...-bp bq-dm dn-fi fj-hf hg-i j-k l-m n-os ot-qp qq-sm sn-uj uk-wf wg-x y-
+ )],
+ 'default ranges'
+ );
+ is_deeply(
+ $index->ranges(\@data, { pagesize => 300 }),
+ [qw(-c d-n o-)],
+ 'large pagesize'
+ );
+};
+
+subtest 'context' => sub {
+ plan tests => 9;
+ my @data = qw(
+ kkeg kl km kmlu knsy koxb kpeo kuaa kuab kuac
+ kuapa kuq kur kux kzb lc lg lgu lgua lguc
+ lguq lgur lgus lgx lka lkq lks lln llq llx
+ );
+ my $index = List::Index->new({ pagesize => 10 }) or return;
+
+ is_deeply(
+ $index->ranges(\@data, { context => 0, length => 5 }),
+ # ranges should match offsets exactly
+ [qw(-kuap. kuapa-lgup lguq-)],
+ 'no context'
+ );
+ is_deeply(
+ $index->ranges(\@data, { context => 0 }),
+ # default length limits to 4 chars
+ [qw(-kuao kuap-lgup lguq-)],
+ 'default length'
+ );
+ is_deeply(
+ $index->ranges(\@data, { context => 1 }),
+ # lookbehinds aren't shorter (kuac<kuap, lguc<lguq)
+ # 'kuap' can advance to 'kuq'
+ [qw(-kup kuq-lgup lguq-)],
+ 'lookahead'
+ );
+ is_deeply(
+ $index->ranges(\@data, { context => 2 }),
+ # allowed to advance to 'kur', but provides no benefits over 'kuq'
+ [qw(-kup kuq-lgup lguq-)],
+ 'minimal lookahead'
+ );
+ is_deeply(
+ $index->ranges(\@data, { 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(\@data, { context => 4 }),
+ [qw(-kt ku-lf lg-)],
+ 'maximal lookahead'
+ );
+ is_deeply(
+ $index->ranges(\@data, { 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(\@data, { context => 9 }),
+ # allow a single (10-9) entry (l-lf = lc) to remain
+ [qw(-k l-lf lg-)],
+ 'lookbehind penalty'
+ );
+ is_deeply(
+ $index->ranges(\@data, { 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 @data = 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
+ );
+ my $index = List::Index->new({ pagesize => 10 }) or return;
+
+ is_deeply(
+ $index->ranges(\@data, { context => 7 }),
+ [qw(-g h i-)],
+ 'large context'
+ );
+ is_deeply(
+ $index->ranges(\@data, { context => 6 }),
+ # 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
+};
+
+subtest 'modulo' => sub {
+ plan tests => 2;
+ my @data = qw( a b ccb ccd cce gf ggg ggh i j );
+ my $index = List::Index->new({ pagesize => 4, context => 0 }) or return;
+ # 10 entries at 4 per page requires 3 pages
+ # so actual target page sizes should be 3,4,3 (not 4,4,2)