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CPAN::Testers - QA of CPAN distributions via cross-platform testing


With the explosive growth and increased interest in the CPAN Testers over the first 5 years, it was felt useful to create this namespace placeholder to house the re-architected next-generation CPAN Testers stack.

This namespace also provides for the consolidation of related work under one unified and easily identifiable umbrella. Co-maintainer permissions in this namespace are freely granted to anyone working on any area of the CPAN Testers infrastructure.


Started in 1998 by Graham Barr and Chris Nandor, the CPAN Testers exist to provide quality assurance of CPAN distributions via cross-platform testing with many versions of perl. Some of our goals include the increase of portability of CPAN distributions and to provide authors with helpful feedback.

Nowadays, it's quite effortless to get involved--even casually--with mature support for CPAN Testing with both CPAN and CPANPLUS. Testing methods ranging from manual to automatic are available.

There are many distributions that comprise the CPAN Testers stack (please forgive my poor artwork). The current architecture is as follows:

   [CPAN-Reporter]      [CPANPLUS-YACSmoke]        [cpanm-reporter]
       (CPAN)                (CPANPLUS)               (cpanminus)
          |                       |                        |
          |                       |                        |
                                  |   CT2.0
                           .   [HTTP]     .
                           .      |       .
                           .  [Metabase]  .
                           . (Data Store) .
                            (Data Store)
          |                       |                        |
          |                       |                        |
 [CPAN-Testers-WWW-Reports]     (APIs)        [CPAN-Testers-WWW-Statistics]    
          |                                                |
 []              []

This a rather simplistic view, but covers the basic flow of test reports into the system, and how the 'cpanstats' database and the core websites are derived.

Smoke Clients

There are additional smokebot applications that sit beyond the CPAN-Reporter, CPANPLUS-YACSmoke and cpanm-report smoker clients, though all use the APIs provided by these hooks into the three primary distribution installers, CPAN, CPANPLUS and cpanminus.

Previously there were standalone scripts, such as 'cpantest' included with CPANPLUS prior to v0.50, which used dedicated test capture code, specifically for the purpose of CPAN Testers. As of CPANPLUS-0.50, this code was removed. In its place a new distribution, CPAN-YACSmoke, was released incorporating new test capture code utilising the new CPANPLUS API.

In 2006 CPAN::Reporter was released, providing smoke testing support for

In 2008, with little work being done to bring CPAN-YACSmoke up to date with the current CPANPLUS API, CPANPLUS-YACSmoke was released, building on the work of CPAN-YACSmoke.

In 2010 a new minmal installer was released. In 2013 a parser, cpanm-reporter, was released that took the output logs from cpanminus and adapted them into test reports that could be submitted to the Metabase. All three installers had their own dedicated smoker clients.

The primary client interfaces for CPAN Testers smoke testing are CPAN-Reporter and CPANPLUS-YACSmoke, though cpanminus-reporter is still young.

In order to submit reports, the clients need to supply test results in a consistent form, so that the data store can parse them and store the relevant parts as necessary. The means to provide a consistent API and transport are provided by Test-Reporter, which includes the transport methods to submit to the appropriate data stores.

CPAN Testers 1.0

CPAN Testers report submissions began on a mailing list. In the early days reports were crafted by hand and sent via a mail client. With the design of CPANPLUS, an automated tool was written to provide test reports that could then be edited before sending. The transport mechanism was SMTP, as provided by Test-Reporter.

For many years this was adequate, with the SMTP transport layer sending reports to the cpan-testers mailing list. The server which received the mails, then provided a read only NNTP service to view the test reports.

In 2008 the number of testers was increasing, and the submission of reports were increasing beyond initial expectations, with over 450,000 reports submitted in November 2009. The storage mechanism provided by NNTP on the servers, had long reached its limit and was no longer scaling with the level of reports being submitted. It was time for a change.

CPAN Testers 2.0

In 2008 the idea for an alternative storage mechanism for CPAN Testers reports was mooted at the Olso QA Hackathon. Out of that came an idea now known as the Metabase. It was the germ of the plan to move CPAN Testers to a HTTP report submission system. At the Birmingham QA Hackathon in 2009, work on the Metabase and a HTTP gateway continued. In December 2009, the admins gave a deadline of 1st March 2010 to switch off SMTP submissions.

Test-Reporter, now provides a delivery mechanism for sending the test report data via a HTTP request, using Test::Reporter::Transport::Metabase, into the Metabase.

The Metabase is now the CPAN Testers 2.0 centralised data store. The Metabase currently sits on an Amazon S3 server, and can cope with many more times the level of throughput than was previously seen with the SMTP delivery mechanism.

As over 1st September 2010, the old SMTP gateway to the old cpan-testers mailing list was closed.

The 'cpanstats' Database

The original 'cpantest' Database began life with a parser reading the NNTP feed once a day and storing metadata in an SQLite database, freely available for all to use.

In 2007 the CPAN Testers Statistics websites extended the parser and created the 'cpanstats' database, which contain more information necessary to drive the statistical analysis. Also initially a SQLite database.

With the overhaul of the CPAN Testers websites in 2008, the 'cpanstats' database became the master database. While the SQLite database was still updated and provided for use by all, the master database was ported into a MySQL database, with tables for uploads and further statistical analysis being added.

The MySQL 'cpanstats' database now provides the following SQLite databases:

  • uploads.db

  • release.db

The old cpanstats.db SQLite database has now been retired, due to errors creating the data with SQLite.

The Websites

Prior to 2002 the CPAN Testers reports were available in their raw form via the NNTP server. In 2002 a new site grouped together the list of reports for each distribution uploaded to CPAN and each CPAN author.

In 2007 the CPAN Testers Statistics site was launched to provide analysis of data regarding reports and to highlight trends in testing.

In 2008, the CPAN Testers websites started receiving an overhaul, with a complete facelift being unveiled in May 2009. The two primary websites, the Reports and Statistics websites are now complimented by the Wiki, Blog, Development, Metabase, Dependencies, Matrix and Analysis websites, with the 'cpanstats' database being used by many other sites for their own data analysis.

In 2010 with the launch of CT2.0 the NNTP feed was deprecated. All reports are now held on the cpantesters server, and can be viewed using their id or guid in styled or raw formats.

Since 2010, various APIs have been released to enable anyone to get at the underlying data and reports to present, analyse and store reports as they wish.

In 2014 the CPAN Testers Admin site was released, to provide authors and testers with a means to 'cancel' reports, where the smoker was submitting incorrect reports, and also for testers to claim the email addresses they have and are using. The latter then feeds into the Leaderboard.

Improvements to the CPAN Testers architecture are always in progress.

For more information on the CPAN Testers please visit the links below:



Mailing Lists





This is the fifth draft of this document. Undoubtedly, there may be various bits that need some adjustments. Feedback is most welcome.


Adam J. Foxson <>, having been involved with the CPAN Testers for over half a decade, is the principal author of Test::Reporter.

Barbie, <> for Miss Barbell Productions <>.

David Golden


  Copyright (C) 2007-2010 Adam J. Foxson and the CPAN Testers
  Copyright (C) 2010-2015 CPAN Testers

This distribution is free software; you can redistribute it and/or modify it under the Artistic License v2.