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Test::Stream - **DEPRECATED** See Test2-Suite instead


This distribution is deprecated in favor of Test2, Test2::Suite, and Test2::Workflow.

See Test::Stream::Manual::ToTest2 for a conversion guide.


This is not a drop-in replacement for Test::More.

Adoption of Test::Stream instead of continuing to use Test::More is a choice. Liberty has been taken to make significant API changes. Replacing use Test::More; with use Test::Stream; will not work for more than the most trivial of test files.

See Test::Stream::Manual::FromTestBuilder if you are coming from Test::More or Test::Simple and want a quick translation.


At the moment you cannot use Test::Stream and Test::Builder based tools in the same test scripts unless you install the TRIAL Test::More version. Once the Test::More trials go stable you will be able to combine tools from both frameworks.


The manual is still being written, but a couple pages are already available.

Migrating from Test::More


How to write tools for Test::Stream


Overview of Test-Stream components



This is the primary interface for loading Test::Stream based tools. This module is responsible for loading bundles and plugins for the tools you want. By default you are required to specify at least 1 plugin or bundle to load. You can subclass Test::Stream to have your own default plugins or bundles.

Bundles and plugins can be used directly, it is not necessary to use Test::Stream to load them.


    use Test::Stream -Classic;

    ok(1, "This is a pass");
    ok(0, "This is a fail");


The '-' above means load the specified bundle, this is the same as:

    use Test::Stream::Bundle::Classic;

    ok(1, "This is a pass");
    ok(0, "This is a fail");



    package My::Loader;
    use strict;
    use warnings;

    use parent 'Test::Stream';

    # The 'default' sub just returns a list of import arguments to use byu
    # default.
    sub default {
        return qw{



use Test::Stream; will fail. You MUST specify at least one bundle or plugin. If you do not specify any then none would be imported and that is obviously not what you want. If you are new to Test::Stream then you should probably start with one of the pre-made bundles:

'-Classic' - The 'Classic' bundle.

This one is probably your best bet when just starting out. This plugin closely resembles the functionality of Test::More.

See Test::Stream::Bundle::Classic.

'-V1' - The bundle used in Test::Streams tests.

This one provides a lot more than the 'Classic' bundle, but is probably not suited to begginers. There are several notable differences from Test::More that can trip you up if you do not pay attention.

See Test::Stream::Bundle::V1.


Future Proofing. If we decide in the future that a specific plugin or tool is harmful we would like to be able to remove it. Making a tool part of the default set will effectively make it unremovable as doing so would break compatability. Instead we have the bundle system, and a set of starter bundles, if a bundle proves ot be harmful we can change the recommendation of the docs.


Test::Stream tools should be created as plugins. This is not enforced, nothing prevents you from writing Test::Stream tools that are not plugins. However writing your tool as a plugin will help your module to play well with other tools. Writing a plugin also makes it easier for you to create private or public bundles that reduce your boilerplate.

Bundles are very simple. At its core a bundle is simply a list of other bundles, plugins, and arguments to those plugins. Much like hash declaration a 'last wins' approach is used; if you load 2 bundles that share a plugin with different arguments, the last set of arguments wins.

Plugins and bundles can be distinguished easily:

    use Test::Stream(
        '-Bundle',                      # Bundle ('-')
        ':Project',                     # Project specific bundle (':')
        'MyPlugin',                     # Plugin name (no prefix)
        '+Fully::Qualified::Plugin',    # (Plugin in unusual path)
        'SomePlugin' => ['arg1', ...],  # (Plugin with args)
        '!UnwantedPlugin',              # Do not load this plugin
        'WantEverything' => '*',        # Load the plugin with all options
        'option' => ...,                # Option to the loader (Test::Stream)



The - prefix indicates that the specified item is a bundle. Bundles live in the Test::Stream::Bundle:: namespace. Each bundle is an independant module. You can specify any number of bundles, or none at all.


The ':' prefix indicates we are loading a project specific bundle, which means the module must be located in t/lib/, lib/, or the paths provided in the TS_LB_PATH environment variable. In the case of ':Project' it will look for Test/Stream/Bundle/ in TS_LB_PATH, t/lib/, then lib/.

This is a good way to create bundles useful to your project, but not really worth putting on CPAN.


Arguments without a prefix are considered to be plugin names. Plugins are assumed to be in Test::Stream::Plugin::, which is prefixed automatically for you.


If you write a plugin, but put it in a non-standard namespace, you can use the fully qualified plugin namespace prefixed by '+'. Apart from the namespace treatment there is no difference in how the plugin is loaded or used.

'SomePlugin' => \@ARGS

Most plugins provide a fairly sane set of defaults when loaded. However some provide extras you need to request. When loading a plugin directly these would be the import arguments. If your plugin is followed by an arrayref the ref contents will be used as load arguments.

Bundles may also specify arguments for plugins. You can override the bundles arguments by specifying your own. In these cases last wins, arguments are never merged. If multiple bundles are loaded, and several specify arguments to the same plugin, the same rules apply.

    use Test::Stream(
        '-BundleFoo',         # Arguments to 'Foo' get squashed by the next bundle
        '-BundleAlsoWithFoo', # Arguments to 'Foo' get squashed by the next line
        'Foo' => [...],       # These args win

This will blacklist the plugin so that it will not be used. The blacklist will block the plugin regardless of where it is listed. The blacklist only effects the statement in which it appears; if you load Test::Stream twice, the blacklist will only apply to the load in which it appears. You cannot override the blacklist items.

'WantEverything' => '*'

This will load the plugin with all options. The '*' gets turned into ['-all'] for you.

'option' => ...

Uncapitalized options without a +, -, or : prefix are reserved for use by the loader. Loaders that subclass Test::Stream can add options of their own.

To define an option in your subclass simply add a sub opt_NAME() method. The method will receive several arguments:

    sub opt_foo {
        my $class = shift;
        my %params = @_;

        my $list  = $params{list};  # List of remaining plugins/args
        my $args  = $params{args};  # Hashref of {plugin => \@args}
        my $order = $params{order}; # Plugins to load, in order
        my $skip  = $params{skip};  # Hashref of plugins to skip {plugin => $bool}

        # Pull our arguments off the list given at load time
        my $foos_arg = shift @$list;

        # Add the 'Foo' plugin to the list of plugins to load, unless it is
        # present in the $args hash in which case it is already in order.
        push @$order => 'Foo' unless $args{'Foo'};

        # Set the args for the plugin
        $args->{Foo} = [$foos_arg];

        $skip{Fox} = 1; # Make sure the Fox plugin never loads.


class => $CLASS

Shortcut for the Test::Stream::Plugin::Class plugin.

skip_without => $MODULE
skip_without => 'v5.008'
skip_without => [$MODULE => $VERSION]

Shortcut for the Test::Stream::Plugin::SkipWithout plugin. Unlike normal specification of a plugin, this APPENDS arguments. This one can be called several time and the arguments will be appended.

Note: specifying 'SkipWithout' the normal way after a call to 'skip_without' will wipe out the argument that have accumulated so far.

srand => $SEED

Shortcut to set the random seed.


For more about plugins and bundles see the following docs:


Test::Stream::Plugin - Provides tools to help write plugins.


Test::Stream::Bundle - Provides tools to help write bundles.


Test::Stream has learned from Test::Builder. For a time it was common for people to write Test::* tools that bundled other Test::* tools with them when loaded. For a short time this seemed like a good idea. This was quickly seen to be a problem when people wanted to use features of multiple testing tools that both made incompatible assumptions about other modules you might want to load.

Test::Stream does not recreate this wild west approach to testing tools and bundles. Test::Stream recognises the benefits of bundles, but provides a much more sane approach. Bundles and Tools are kept separate, this way you can always use tools without being forced to adopt the authors ideal bundle.


This is a list of environment variables Test::Stream looks at:


This can be used to set the output formatter. By default Test::Stream::Formatter::TAP is used.

Normally 'Test::Stream::Formatter::' is prefixed to the value in the environment variable:

    $ TS_FORMATTER='TAP' perl test.t     # Use the Test::Stream::Formatter::TAP formatter
    $ TS_FORMATTER='Foo' perl test.t     # Use the Test::Stream::Formatter::Foo formatter

If you want to specify a full module name you use the '+' prefix:

    $ TS_FORMATTER='+Foo::Bar' perl test.t     # Use the Foo::Bar formatter

Some IPC drivers make use of temporary directories, this variable will tell Test::Stream to keep the directory when the tests are complete.


This allows you to provide paths where Test::Stream will search for project specific bundles. These paths are NOT added to @INC.


This is used by the Test::Stream::Plugin::Compare plugin. This specifies the max number of differences to show when data structures do not match.


This is used to set the width of the terminal. This is used when building tables of diagnostics. The default is 80, unless Term::ReadKey is installed in which case the value is determined dynamically.


This is used by the Test::Stream::Plugin::Spec plugin to specify which test block should be run, only the specified block will be run.


This only works when used with the Test::Stream::Plugin::SRand plugin. This lets you specify the random seed to use.


This is typically set by TAP::Harness and other harnesses. You should not need to set this yourself.


This is typically set by TAP::Harness and other harnesses. You should not need to set this yourself.


This variable is specified by Trace::Mask. Test::Stream uses the Trace::Mask specification to mask some stack frames from traces generated by Trace::Mask compliant tools. Setting this variable will force a full stack trace whenever a trace is produced.


The source code repository for Test::Stream can be found at


Chad Granum <>


Chad Granum <>


Copyright 2015 Chad Granum <>.

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