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Re: Diagnostic messages in Test::Deep

by Athanasius (Bishop)
on Jul 21, 2015 at 07:01 UTC ( #1135542=note: print w/replies, xml ) Need Help??


in reply to Diagnostic messages in Test::Deep

Hello KeighleHawk,

Naturally, the array can be returned in random order.

Actually, the elements of an array are always in a fixed order — that’s the nature of arrays. I think you mean the array will be populated in a random order?

...part of the structure I am comparing includes an array of hashes.... Initially, I was using a sort on one of the hash fields, but as my data set increased, I started to hit return values with different hash structures so my sorting column needed to change.

I don’t understand this. If you are comparing an array of hashes with an unordered list of hashes, it seems to me that you have to proceed in two steps:

  1. Pair the hashes;
  2. For each pair, the hashes are equal if and only if they contain exactly the same key/value pairs (in any order).

From which (I think) it follows that a generic procedure is all that’s required:

#! perl use strict; use warnings; use Test::More tests => 2; use Test::Deep; my @x = ( { j => 12, a => 1 }, { b => [1, 11] }, { c => 3 } ); my @y = ( { c => 3 }, { b => [0, 11] }, { a => 1, j => 12 } ); cmp_deeply( \@x, bag(@y), 'Deep' ); print '-' x 20, "\n"; is_deeply( sort_hash(@x), sort_hash(@y), 'More' ); sub sort_hash { return [ sort { (sort keys %$a)[0] cmp (sort keys %$b)[0] } @_ ]; }

Output:

16:56 >perl 1314_SoPW.pl 1..2 not ok 1 - Deep # Failed test 'Deep' # at 1314_SoPW.pl line 22. # Comparing $data as a Bag # Missing: 1 reference # Extra: 1 reference -------------------- not ok 2 - More # Failed test 'More' # at 1314_SoPW.pl line 24. # Structures begin differing at: # $got->[1]{b}[0] = '1' # $expected->[1]{b}[0] = '0' # Looks like you failed 2 tests of 2. 16:56 >

Clearly, Test::More::is_deeply returns a much more informative message on failure than does Test::Deep::cmp_deeply — as you have stated. But in what way does my sub sort_hash fall short of the functionality provided by Test::Deep::bag for your purposes? Please clarify by providing sample input for which the comparison with Test::Deep::bag will work, but a generic comparison based on hash keys will not.

Hope that helps,

Athanasius <°(((><contra mundum Iustus alius egestas vitae, eros Piratica,

Replies are listed 'Best First'.
Re^2: Diagnostic messages in Test::Deep
by KeighleHawk (Scribe) on Jul 21, 2015 at 13:31 UTC
    yes, the array can be populated in random order :-).

    The data set is slightly different than your example. The keys for each hash within the test run are the same. They differ between runs/tests.

    Test 1 sample.

    $got = [ { key_1 => "A", key_2 => "CC"} , { key_1 => "B", key_2 => "CC"} ] $expected = [ { key_1 => "B", key_2 => "CC"} , { key_1 => "A", key_2 => "CC"} ]

    I want these to evaluate as equal, and they do with code like this (similar to yours):

    return is deeply ( $got ? [ sort {$a->{key_1} cmp $b->{key_1}} $got ] : [] , $expected ? [ sort {$a->{key_1} cmp $b->{key_1}} $expected ] : [] , "Test array of hashes"

    (the ternary operator is there because "no data returned" is also a valid/possible response).

    The problem arises with Test 2 which has the following data:

    $got = [ { key_3 => "A", key_2 => "CC"} , { key_3 => "B", key_2 => "CC"} ] $expected = [ { key_3 => "B", key_2 => "CC"} , { key_3 => "A", key_2 => "CC"} ]

    The problem is the sorting key name has changed from 'key_1' to 'key_3' so my sort:

    sort {$a->{key_1} cmp $b->{key_1}}

    fails on the second data set. I could pass in the key names as variables, but was hoping to avoid that, especially since Test::Deep->bag() does exactly what I want.

    The working Test::Deep code looks like this:

    return = cmp_deeply ( $got ? [ $got ] : [] , bag ( $expected ? $expected : () ) );

    (different brackets on bag due to return type, I need to double check that...)

    So Test::Deep->bag() works for me because it does magic I don't have to when deciding how to sort the second array.

    Robert Kuropkat

      OK, I think I understand now; I hadn’t realised that separate hashes within the one array could legitimately contain the same keys with different values.

      I still think a generic procedure will work, it just needs a comprehensive sorting algorithm:

      #! perl use strict; use warnings; use Test::More tests => 2; use Test::Deep; my @x = ( { key_3 => 'A', key_2 => 'CC', key_4 => 'E', key_5 => 0 }, { key_3 => 'A', key_2 => 'DD', key_4 => 'F' }, ); my @y = ( { key_3 => 'A', key_2 => 'DD', key_4 => 'F' }, { key_5 => 0, key_3 => 'A', key_2 => 'CC', key_4 => 'E' }, ); cmp_deeply( \@x, bag(@y), 'Deep' ); print '-' x 20, "\n"; is_deeply( my_sort(@x), my_sort(@y), 'More' ); sub my_sort { my $f = sub { my @keys_a = sort keys %$a; my @keys_b = sort keys %$b; return -1 if @keys_a < @keys_b; return 1 if @keys_a > @keys_b; my $result = 0; $result ||= $keys_a[$_] cmp $keys_b[$_] || $a->{$keys_a[$_]} cmp $b->{$keys_b[$_]} for 0 .. $#k +eys_a; return $result; }; return [ sort $f @_ ]; }

      (For the basic idea, see perlfaq4#How-do-I-sort-an-array-by-anything.) Output:

      14:38 >perl 1314a_SoPW.pl 1..2 ok 1 - Deep -------------------- ok 2 - More 14:38 >

      Disclaimer: I’ve tested this only minimally; there may be corner cases I haven’t found. But I think this should allow you to return to using Test::More::is_deeply to get the benefit of its superior failure messages.

      Hope that helps,

      Athanasius <°(((><contra mundum Iustus alius egestas vitae, eros Piratica,

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