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Test::Specio - Test helpers for Specio


version 0.48


  use Test::Specio qw( test_constraint :vars );

      t('Foo'), {
          accept => [ 'foo', 'bar' ],
          reject => [ 42,    {}, $EMPTY_STRING, $HASH_REF ],


This package provides some helper functions and variables for testing Specio types.


This module provides the following exports:

test_constraint( $type, $tests, [ $describer ] )

This subroutine accepts two arguments. The first should be a Specio type object. The second is hashref which can contain the keys accept and reject. Each key should contain an arrayref of values which the type accepts or rejects.

The third argument is optional. This is a sub reference which will be called to generate a description of the value being tested. This defaults to calling this package's describe sub, but you can provide your own.


Given a value, this subroutine returns a string describing that value in a useful way for test output. It know about the various classes used for the variables exported by this package and will do something intelligent when such a variable.


This subroutine returns a hashref containing test variables for all builtin types. The hashref has a form like this:

      Bool => {
          accept => [
          reject => [
      Maybe => {...},

You need to pass in a glob, an object which overloads globification, and an object which overloads globification to return an open filehandle. See below for more details on how to create these things.


This module also exports many variables containing values which are useful for testing constraints. Note that references are always empty unless stated otherwise. You can import these variables individually or import all of them with the :vars import tag.

  • $ZERO

  • $ONE

  • $INT

    An arbitrary positive integer.

  • $NEG_INT

    An arbitrary negative integer.

  • $NUM

    An arbitrary positive non-integer number.

  • $NEG_NUM

    An arbitrary negative non-integer number.



    An arbitrary non-empty string.


    An arbitrary string which contains a number.


    An string containing an integer followed by a newline.


    An string containing a newline followed by an integer.



    A reference containing a reference to a scalar.





  • $FH

    An opened filehandle.


    An opened IO::File object.

  • $REGEX

    A regex created with qr//.


    A regex created with qr// that was then blessed into class.


    A non-regex blessed into the Regexp class which Perl uses internally for qr// objects.


    An arbitrary object.

  • $UNDEF


    A string containing a loaded package name.


    An object which overloads boolification to return true.


    An object which overloads boolification to return false.


    An object which overloads stringification to return an empty string.


    An object which overloads stringification to return a non-empty string.


    An object which overloads stringification to return a loaded package name.








    An object which overloads scalar dereferencing to return a non-empty string.


    An object which overloads array dereferencing to return a non-empty array.


    An object which overloads hash dereferencing to return a non-empty hash.

Globs and the _T::GlobOverload package

To create a glob you can pass around for tests, use this code:

  my $GLOB = do {
      no warnings 'once';

The _T::GlobOverload package is defined when you load Test::Specio so you can create your own glob overloading objects. Such objects cannot be exported because the glob they return does not transfer across packages properly.

You can create such a variable like this:

  local *FOO;
  my $GLOB_OVERLOAD = _T::GlobOverload->new( \*FOO );

If you want to create a glob overloading object that returns a filehandle, do this:

  local *BAR;
  open BAR, '<', $^X or die "Could not open $^X for the test";
  my $GLOB_OVERLOAD_FH = _T::GlobOverload->new( \*BAR );


Bugs may be submitted at


The source code repository for Specio can be found at


Dave Rolsky <>


This software is Copyright (c) 2012 - 2022 by Dave Rolsky.

This is free software, licensed under:

  The Artistic License 2.0 (GPL Compatible)

The full text of the license can be found in the LICENSE file included with this distribution.