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App::Cmd::Tester - for capturing the result of running an app


version 0.336


  use Test::More tests => 4;
  use App::Cmd::Tester;

  use YourApp;

  my $result = test_app(YourApp => [ qw(command --opt value) ]);

  like($result->stdout, qr/expected output/, 'printed what we expected');

  is($result->stderr, '', 'nothing sent to sderr');

  is($result->error, undef, 'threw no exceptions');

  my $result = test_app(YourApp => [ qw(command --opt value --quiet) ]);

  is($result->output, '', 'absolutely no output with --quiet');


One of the reasons that user-executed programs are so often poorly tested is that they are hard to test. App::Cmd::Tester is one of the tools App-Cmd provides to help make it easy to test App::Cmd-based programs.

It provides one routine: test_app.


This library should run on perls released even a long time ago. It should work on any version of perl released in the last five years.

Although it may work on older versions of perl, no guarantee is made that the minimum required version will not be increased. The version may be increased for any reason, and there is no promise that patches will be accepted to lower the minimum required perl.



Note: while test_app is a method, it is by default exported as a subroutine into the namespace that uses App::Cmd::Tester. In other words: you probably don't need to think about this as a method unless you want to subclass App::Cmd::Tester.

  my $result = test_app($app_class => \@argv_contents);

This will locally set @ARGV to simulate command line arguments, and will then call the run method on the given application class (or application). Output to the standard output and standard error filehandles will be captured.

$result is an App::Cmd::Tester::Result object, which has methods to access the following data:

  stdout - the output sent to stdout
  stderr - the output sent to stderr
  output - the combined output of stdout and stderr
  error  - the exception thrown by running the application, or undef
  run_rv - the return value of the run method (generally irrelevant)
  exit_code - the numeric exit code that would've been issued (0 is 'okay')

The output is captured using IO::TieCombine, which can ensure that the ordering is preserved in the combined output, but can't capture the output of external programs. You can reverse these tradeoffs by using App::Cmd::Tester::CaptureExternal instead.


Ricardo Signes <>


This software is copyright (c) 2023 by Ricardo Signes.

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