perl - Test::More is_deeply does not pretty-print array/hashrefs when comparing against strings -

when test::more compares arrayrefs , hashrefs each other, corresponding diagnostic message informative , shows first index structures differ, regardless of nesting depth. however, when comparing arrayref or hashref simple scalar, produces stringified scalar (with memory address , reference type) in diagnostic message, harder interpret.

is there way configure test::more pretty-print array or hashrefs in custom way (such using data::dumper)?

here's example 2 test cases. first gives insight present in program unexpected. second informs user of type mismatch between string , arrayref, not print items in arrayref.

#!/usr/bin/env perl use strict; use warnings; use test::more tests => 2;  is_deeply(     {         => [5],     },     {         => [5, 6, 8],     },     'compare 2 hashrefs structurally (very informative output)', );  is_deeply(     [5, 6, 8],     "",     'compare 2 "incompatible" values structurally (uninformative output)', ); 

and tap output:

1..2 not ok 1 - compare 2 hashrefs structurally (very informative output) #   failed test 'compare 2 hashrefs structurally (very informative output)' #   @ test-more-failure.pl line 6. #     structures begin differing at: #          $got->{a}[1] = not exist #     $expected->{a}[1] = '6' not ok 2 - compare 2 "incompatible" values structurally (uninformative output) #   failed test 'compare 2 "incompatible" values structurally (uninformative output)' #   @ test-more-failure.pl line 16. #     structures begin differing at: #          $got = array(0x7fe66b82cde8) #     $expected = '' # looks failed 2 tests of 2. 

looking @ implementation of is_deeply in test::more, there doesn't seem way use custom pretty-printer or configure verbosity of module. @ least none that's obvious me.

here happens when compare reference , non-reference:

https://metacpan.org/source/exodist/test-simple-1.302062/lib/test/more.pm#l1121

it seems calling _format_stack({vals => [...]}) instead of _format_stack(...)

https://metacpan.org/source/exodist/test-simple-1.302062/lib/test/more.pm#l1139

tl;dr use is_deeply($this, $that) || diag explain $this on case case basis.

hi. i'm 1 blame is_deeply. it's deliberately designed not vomit out potentially enormous data structure when fails. instead stops @ first difference. reason don't want globally make is_deeply dump arguments. if types wrong, if expected apples , got zebras, there's not point in knowing how many zebras , life stories.

there no supported way change diagnostics, sorry, , it's unlikely there be. test::more being replaced test2. test::more implemented on top of test2, doesn't take advantage of features backwards compatibility reasons.

you can use test2::bundle::more more direct access test2's features, not 100% compatible, , displays similar how is_deeply does. however, more flexible , can figure out way alter diagnostic behavior. test2::compare.

---

back problem... use explain on case case basis. explain uses data::dumper, configured properly, dump data structure. since test::more functions return whether passed or failed, can write is_deeply($this, $that) || diag explain $this. example...

my $stuff = [5, 6, 8]; is_deeply $stuff, "" || diag explain $stuff;  not ok 2 #   failed test @ /users/schwern/tmp/test.plx line 17. #     structures begin differing at: #          $got = array(0x7f80b3803078) #     $expected = '' # [ #   5, #   6, #   8 # ] 

diag how print failure diagnostics (it's more polite way print stderr).