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Test::Alien - Testing tools for Alien modules


version 2.83


Test commands that come with your Alien:

 use Test2::V0;
 use Test::Alien;
 use Alien::patch;
 alien_ok 'Alien::patch';
 run_ok([ 'patch', '--version' ])
   # we only accept the version written
   # by Larry ...
   ->out_like(qr{Larry Wall});

Test that your library works with XS:

 use Test2::V0;
 use Test::Alien;
 use Alien::Editline;
 alien_ok 'Alien::Editline';
 my $xs = do { local $/; <DATA> };
 xs_ok $xs, with_subtest {
   my($module) = @_;
   ok $module->version;
 #include "EXTERN.h"
 #include "perl.h"
 #include "XSUB.h"
 #include <editline/readline.h>
 const char *
 version(const char *class)
   return rl_library_version;
 const char *version(class);
     const char *class;

Test that your library works with FFI::Platypus:

 use Test2::V0;
 use Test::Alien;
 use Alien::LibYAML;
 alien_ok 'Alien::LibYAML';
 ffi_ok { symbols => ['yaml_get_version'] }, with_subtest {
   my($ffi) = @_;
   my $get_version = $ffi->function(yaml_get_version => ['int*','int*','int*'] => 'void');
   $get_version->call(\my $major, \my $minor, \my $patch);
   like $major, qr{[0-9]+};
   like $minor, qr{[0-9]+};
   like $patch, qr{[0-9]+};


This module provides tools for testing Alien modules. It has hooks to work easily with Alien::Base based modules, but can also be used via the synthetic interface to test non Alien::Base based Alien modules. It has very modest prerequisites.

Prior to this module the best way to test a Alien module was via Test::CChecker. The main downside to that module is that it is heavily influenced by and uses ExtUtils::CChecker, which is a tool for checking at install time various things about your compiler. It was also written before Alien::Base became as stable as it is today. In particular, Test::CChecker does its testing by creating an executable and running it. Unfortunately Perl uses extensions by creating dynamic libraries and linking them into the Perl process, which is different in subtle and error prone ways. This module attempts to test the libraries in the way that they will actually be used, via either XS or FFI::Platypus. It also provides a mechanism for testing binaries that are provided by the various Alien modules (for example Alien::gmake and Alien::patch).

Alien modules can actually be useable without a compiler, or without FFI::Platypus (for example, if the library is provided by the system, and you are using FFI::Platypus, or if you are building from source and you are using XS), so tests with missing prerequisites are automatically skipped. For example, "xs_ok" will automatically skip itself if a compiler is not found, and "ffi_ok" will automatically skip itself if FFI::Platypus is not installed.



 alien_ok $alien, $message;
 alien_ok $alien;

Load the given Alien instance or class. Checks that the instance or class conforms to the same interface as Alien::Base. Will be used by subsequent tests. The $alien module only needs to provide these methods in order to conform to the Alien::Base interface:


String containing the compiler flags


String containing the linker and library flags


List of dynamic libraries. Returns empty list if the Alien module does not provide this.


Directory containing tool binaries. Returns empty list if the Alien module does not provide this.

If your Alien module does not conform to this interface then you can create a synthetic Alien module using the "synthetic" function.


 my $alien = synthetic \%config;

Create a synthetic Alien module which can be passed into "alien_ok". \%config can contain these keys (all of which are optional):


String containing the compiler flags.


String containing the static compiler flags (optional).


String containing the linker and library flags.


String containing the static linker flags (optional).


List reference containing the dynamic libraries.


Tool binary directory.


Runtime properties.

See Test::Alien::Synthetic for more details.


 my $run = run_ok $command;
 my $run = run_ok $command, $message;

Runs the given command, falling back on any Alien::Base#bin_dir methods provided by Alien modules specified with "alien_ok".

$command can be either a string or an array reference.

Only fails if the command cannot be found, or if it is killed by a signal! Returns a Test::Alien::Run object, which you can use to test the exit status, output and standard error.

Always returns an instance of Test::Alien::Run, even if the command could not be found.


 xs_ok $xs;
 xs_ok $xs, $message;

Compiles, links the given XS code and attaches to Perl.

If you use the special module name TA_MODULE in your XS code, it will be replaced by an automatically generated package name. This can be useful if you want to pass the same XS code to multiple calls to xs_ok without subsequent calls replacing previous ones.

$xs may be either a string containing the XS code, or a hash reference with these keys:


The XS code. This is the only required element.


Extra ExtUtils::ParseXS arguments passed in as a hash reference.


The compile check that should be done prior to attempting to build. Should be one of have_compiler or have_cplusplus. Defaults to have_compiler.


Hash to override values normally provided by Config.


Extra The ExtUtils::CBuilder arguments passed in as a hash reference.

Extra The ExtUtils::CBuilder arguments passed in as a hash reference.


Spew copious debug information via test note.

You can use the with_subtest keyword to conditionally run a subtest if the xs_ok call succeeds. If xs_ok does not work, then the subtest will automatically be skipped. Example:

 xs_ok $xs, with_subtest {
   # skipped if $xs fails for some reason
   my($module) = @_;
   is $module->foo, 1;

The module name detected during the XS parsing phase will be passed in to the subtest. This is helpful when you are using a generated module name.

If you need to test XS C++ interfaces, see Test::Alien::CPP.

Caveats: xs_ok uses ExtUtils::ParseXS, which may call exit under certain error conditions. While this is not really good thing to happen in the middle of a test, it usually indicates a real failure condition, and it should return a failure condition so the test should still fail overall.

[version 2.53]

As of version 2.53, xs_ok will only remove temporary generated files if the test is successful by default. You can force either always or never removing the temporary generated files using the TEST_ALIEN_ALWAYS_KEEP environment variable (see "ENVIRONMENT" below).


 ffi_ok \%opt;
 ffi_ok \%opt, $message;

Test that FFI::Platypus works.

\%opt is a hash reference with these keys (all optional):


List references of symbols that must be found for the test to succeed.


Ignores symbols that aren't found. This affects functions accessed via FFI::Platypus#attach and FFI::Platypus#function methods, and does not influence the symbols key above.


Set the language. Used primarily for language specific native types.


Set the API. api = 1 requires FFI::Platypus 0.99 or later. This option was added with Test::Alien version 1.90, so your use line should include this version as a safeguard to make sure it works:

 use Test::Alien 1.90;
 ffi_ok ...;

As with "xs_ok" above, you can use the with_subtest keyword to specify a subtest to be run if ffi_ok succeeds (it will skip otherwise). The FFI::Platypus instance is passed into the subtest as the first argument. For example:

 ffi_ok with_subtest {
   my($ffi) = @_;
   is $ffi->function(foo => [] => 'void')->call, 42;


 helper_ok $name;
 helper_ok $name, $message;

Tests that the given helper has been defined.


[version 2.52]

 plugin_ok $plugin_name, $message;
 plugin_ok [$plugin_name, @args], $message;

This applies an Alien::Build::Plugin to the interpolator used by "helper_ok", "interpolate_template_is" and "interpolate_run_ok" so that you can test with any helpers that plugin provides. Useful, for example for getting %{configure} from Alien::Build::Plugin::Build::Autoconf.


 interpolate_template_is $template, $string;
 interpolate_template_is $template, $string, $message;
 interpolate_template_is $template, $regex;
 interpolate_template_is $template, $regex, $message;

Tests that the given template when evaluated with the appropriate helpers will match either the given string or regular expression.


[version 2.52]

 my $run = interpolate_run_ok $command;
 my $run = interpolate_run_ok $command, $message;

This is the same as "run_ok" except it runs the command through the interpolator first.



If this is defined then it will override the built in logic that decides if the temporary files generated by "xs_ok" should be kept when the test file terminates. If set to true the generated files will always be kept. If set to false, then they will always be removed.


By default, this module will warn you if some tools are used without first invoking "alien_ok". This is usually a mistake, but if you really do want to use one of these tools with no aliens loaded, you can set this environment variable to false.




Author: Graham Ollis <>


Diab Jerius (DJERIUS)

Roy Storey (KIWIROY)

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Shoichi Kaji (SKAJI)

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Paul Evans (leonerd, PEVANS)

Håkon Hægland (hakonhagland, HAKONH)

nick nauwelaerts (INPHOBIA)

Florian Weimer


This software is copyright (c) 2011-2022 by Graham Ollis.

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