Test::Deep::Filter - Perform a filter on a matched element before doing sub-matching


version 0.001001


This module exists so that one can apply some kind of transform of the content of some node, before applying a deep testing structure against it.

This is especially the kind of domain Test::Deep::YAML and Test::Deep::JSON are targeted at, but implemented in a more generic way.

  cmp_deeply( $got, { payload => filter(\&decode_json, { x => 1 }) } )

This would perform matching against a Perl data structure called $got, and find its key called payload, and, if existing, filter the key via &decode_json, and then compare the resulting structure with { x => 1 }.

This would in theory be equivalent to:

  cmp_deeply( $got, { payload => json({ x => 1 }) } )

Except may be tailored for what ever local decoding scheme you may require, e.g.:

  cmp_deeply( $got, {
      payload => filter(sub {
        my ( $got ) = @_;
        return parse_ini( $got );
      }, { x => 1 })



  my $object = filter( \&filter_function, $expected );

  cmp_deeply( $got, filter( \&filter_function, $expected ));

A filter can take any value into &filter_function, and return any value and the Test::Deep infrastructure will handle the rest.

If the value cannot be parsed, or is of a type you cannot handle, or the internal logic returns an invalid value ( including any failures in internal logic that fail to parse, etc) then you must cause the function to throw an exception with "die", and the nested $expected will be assumed to be false.

The "die" message will be used as a diagnostic for why the match failed.


Kent Fredric <>


This software is copyright (c) 2017 by Kent Fredric <>.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.