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Config::Model::Tester(3pm) User Contributed Perl Documentation Config::Model::Tester(3pm)


Config::Model::Tester - Test framework for Config::Model


version 4.007


In your test file (typically "t/model_test.t"):

 use warnings;
 use strict;
 use Config::Model::Tester ;
 use ExtUtils::testlib;
 run_tests() ;

Run tests with:

 perl t/model_test.t [ --log ] [--error] [--trace] [ subtest [ test_case ] ]


This class provides a way to test configuration models with tests files. This class was designed to tests several models and run several tests cases per model.

A specific layout for test files must be followed.

Sub test specification

Each subtest is defined in a file like:


This file specifies that "app-name" (which is defined in "lib/Config/Model/*.d" directory) is used for the test cases defined in the "*" file. The model to test is inferred from the application name to test.

This file contains a list of test case (explained below) and expects a set of files used as test data. The layout of these test data files is explained in next section.

Simple test file layout

Each test case is represented by a configuration file (not a directory) in the "*-examples" directory. This configuration file is used by the model to test and is copied as "$confdir/$conf_file_name" using the test data structure explained below.

In the example below, we have 1 app model to test: "lcdproc" and 2 tests cases. The app name matches the file specified in "lib/Config/Model/*.d" directory. In this case, the app name matches "lib/Config/Model/system.d/lcdproc"

 |-- model_test.t
 \-- model_tests.d           # do not change directory name
     |--   # subtest specification for lcdproc app
     \-- lcdproc-examples
         |-- t0              # test case t0
         \-- LCDD-0.5.5      # test case for older LCDproc

Subtest specification is written in "" file (i.e. this module looks for files named like "<app-name>>").

Subtests data is provided in files in directory "lcdproc-examples" ( i.e. this modules looks for test data in directory "<model-name>-examples>". "" contains instructions so that each file is used as a "/etc/LCDd.conf" file during each test case.

"" can contain specifications for more test cases. Each test case requires a new file in "lcdproc-examples" directory.

See "Examples" for a link to the actual LCDproc model tests

Test file layout for multi-file configuration

When a configuration is spread over several files, each test case is provided in a sub-directory. This sub-directory is copied in "conf_dir" (a test parameter as explained below)

In the example below, the test specification is written in "". Dpkg layout requires several files per test case. "" contains instructions so that each directory under "dpkg-examples" is used.

 \--         # subtest specification
 \-- dpkg-examples
     \-- libversion            # example subdir, used as test case name
         \-- debian            # directory for used by test case
             |-- changelog
             |-- compat
             |-- control
             |-- copyright
             |-- rules
             |-- source
             |   \-- format
             \-- watch

See "Examples" for a link to the (many) Dpkg model tests

More complex file layout

Each test case is a sub-directory on the "*-examples" directory and contains several files. The destination of the test files may depend on the system (e.g. the OS). For instance, system wide "ssh_config" is stored in "/etc/ssh" on Linux, and directly in "/etc" on MacOS.

These files are copied in a test directory using a "setup" parameter in test case specification.

Let's consider this example of 2 tests cases for ssh:

 |-- ssh-examples
     \-- basic
         |-- system_ssh_config
         \-- user_ssh_config

Unfortunately, "user_ssh_config" is a user file, so you need to specify where is located the home directory of the test with another global parameter:

  home_for_test => '/home/joe' ;

For Linux only, the "setup" parameter is:

 setup => {
   system_ssh_config => '/etc/ssh/ssh_config',
   user_ssh_config   => "~/.ssh/config"

On the other hand, system wide config file is different on MacOS and the test file must be copied in the correct location. When the value of the "setup" hash is another hash, the key of this other hash is used as to specify the target location for other OS (as returned by Perl $^O variable:

      setup => {
        'system_ssh_config' => {
            'darwin' => '/etc/ssh_config',
            'default' => '/etc/ssh/ssh_config',
        'user_ssh_config' => "~/.ssh/config"

"systemd" is another beast where configuration files can be symlinks to "/dev/null" or other files. To emulate this situation, use an array as setup target:

  setup => {
      # test data file => [ link (may be repeated), ..       link(s) target contains test data ]
      'ssh.service' => [ '/etc/systemd/system/sshd.service', '/lib/systemd/system/ssh.service' ]

This will result in a symlink like:

   -> /absolute_path_to/wr_root/model_tests/test-sshd-service/lib/systemd/system/ssh.service

See the actual Ssh and Sshd model tests <>

Basic test specification

Each model subtest is specified in "<app>". This file must return a data structure containing the test specifications. Each test data structure contains global parameters (Applied to all tests cases) and test cases parameters (parameters are applied to the test case)

 use strict;
 use warnings;
   # global parameters
   # config file name (used to copy test case into test wr_root/model_tests directory)
   conf_file_name => "fstab",
   # config dir where to copy the file (optional)
   conf_dir => "etc",
   # home directory for this test
   home_for_test => '/home/joe'
   tests =>  [
       # test case 1
       name => 'my_first_test',
       # other test case parameters
       # test case 2
       name => 'my_second_test',
       # other test case parameters
     # ...
 # do not add 1; at the end of the file

In the example below, "t0" file is copied in "wr_root/model_tests/test-t0/etc/fstab".

 use strict;
 use warnings;
   # list of tests.
   tests => [
       # test name
       name => 't0',
       # add optional specification here for t0 test
       name => 't1',
       # add optional specification here for t1 test

You can suppress warnings by specifying "no_warnings => 1" in each test case. On the other hand, you may also want to check for warnings specified to your model. In this case, you should avoid specifying "no_warnings" here and specify warning tests or warning filters as mentioned below.

See actual fstab test <>.

Skip a test

A test file can be skipped using "skip" global test parameter.

In this example, test is skipped when not running on a Debian system:

 eval { require AptPkg::Config; };
 my $skip = ( $@ or not -r '/etc/debian_version' ) ? 1 : 0;
   skip => $skip,
   tests => [ ] ,

Internal tests or backend tests

Some tests require the creation of a configuration class dedicated for test (typically to test corner cases on a backend).

This test class can be created directly in the test specification by specifying tests classes in "config_classes" global test parameter in an array ref. Each array element is a data structure that use create_config_class parameters. See for instance the layer test <> or the test for shellvar backend <>.

In this case, no application exist for such classes so the model to test must be specified in a global test parameter:

  return {
    config_classes => [ { name => "Foo", element => ... } , ... ],
    model_to_test => "Foo",
    tests => [ ... ]

Test specification with arbitrary file names

In some models, like "Multistrap", the config file is chosen by the user. In this case, the file name must be specified for each tests case:

   tests => [ {
       name        => 'arm',
       config_file => '/home/foo/my_arm.conf',
       check       => {},

See the actual multistrap test <>.

Backend argument

Some application like systemd requires a backend argument specified by user (e.g. a service name for systemd). The parameter "backend_arg" can be specified to emulate this behavior.

Re-use test data

When the input data for test is quite complex (several files), it may be interesting to re-use these data for other test cases. Knowing that test names must be unique, you can re-use test data with "data_from" parameter. For instance:

  tests => [
        name  => 'some-test',
        # ...
        name  => 'some-other-test',
        data_from  => 'some-test',    # re-use data from test above
        # ...

See plainfile backend test <> for a real life example.

Likewise, it may be useful to re-use test data from another group of test. Lets see this example from "":

        name => 'transmission',
        data_from_group => 'systemd', # i.e from ../systemd-examples

"data_from" and "data_from_group" can be together.

Test scenario

Each subtest follow a sequence explained below. Each step of this sequence may be altered by adding test case parameters in "<model-to-test>":

  • Setup test in "wr_root/model_tests/<subtest name>/". If your configuration file layout depend on the target system, you will have to specify the path using "setup" parameter. See "More complex file layout".
  • Create configuration instance, load config data and check its validity. Use "load_check => 'no'" if your file is not valid.
  • Check for config data warnings. You should pass the list of expected warnings that are emitted through Log::Log4perl. The array ref is passed as is to the "expect" function of "expect" in Test::Log::Lo4Perl. E.g:

        log4perl_load_warnings => [
             [ 'Tree.Node', (warn => qr/deprecated/) x 2 ]  ,
             [ 'Tree.Element.Value' , ( warn => qr/skipping/) x 2 ]

    The Log classes are specified in "cme/Logging".

    Log levels below "warn" are ignored.

    Note that log tests are disabled when "--log" option is used, hence all warnings triggered by the tests are shown.

    Config::Model is currently transitioning from traditional "warn" to warn logs. To avoid breaking all tests based on this module, the warnings are emitted through Log::Log4perl only when $::_use_log4perl_to_warn is set. This hack will be removed once all warnings checks in tests are ported to log4perl checks.

  • DEPRECATED. Check for config data warning. You should pass the list of expected warnings. E.g.

        load_warnings => [ qr/Missing/, (qr/deprecated/) x 3 , ],

    Use an empty array_ref to mask load warnings.

  • Optionally run update command:

     update => {
        returns => 'foo' , # optional
        no_warnings => [ 0 | 1 ], # default 0
        quiet => [ 0 | 1], # default 0, passed to update method
        load4perl_update_warnings => [ ... ] # Test::Log::Log4perl::expect arguments


  • "returns" is the expected return value (optional).
  • "no_warnings" can be used to suppress the warnings coming from Config::Model::Value. Note that "no_warnings => 1" may be useful for less verbose test.
  • "quiet" to suppress progress messages during update.
  • "log4perl_update_warnings" is used to check the warnings produced during update. The argument is passed to "expect" function of Test::Log::Log4perl. See "load_warnings" parameter above for more details.
  • DEPRECATED. "update_warnings" is an array ref of quoted regexp (See qr operator) to check the warnings produced during update. Please use "log4perl_update_warnings" instead.

All other arguments are passed to "update" method.

  • Optionally load configuration data. You should design this config data to suppress any error or warning mentioned above. E.g:

        load => 'binary:seaview Synopsis="multiplatform interface for sequence alignment"',

    See Config::Model::Loader for the syntax of the string accepted by "load" parameter.

  • Optionally, run a check before running apply_fix (if any). This step is useful to check warning messages:

       check_before_fix => {
          dump_errors   => [ ... ] # optional, see below
          log4perl_dump_warnings => [ ... ] # optional, see below

    Use "dump_errors" if you expect issues:

      check_before_fix => {
        dump_errors =>  [
            # the issues  and a way to fix the issue using Config::Model::Node::load
            qr/mandatory/ => 'Files:"*" Copyright:0="(c) foobar"',
            qr/mandatory/ => ' License:FOO text="foo bar" ! Files:"*" License short_name="FOO" '

    Likewise, specify any expected warnings:

      check_before_fix => {
            log4perl_dump_warnings => [ ... ],

    "log4perl_dump_warnings" passes the array ref content to "expect" function of Test::Log::Log4perl.

    Both "log4perl_dump_warnings" and "dump_errors" can be specified in "check_before_fix" hash.

  • Optionally, call apply_fixes:

        apply_fix => 1,
  • Call dump_tree to check the validity of the data after optional "apply_fix". This step is not optional.

    As with "check_before_fix", both "dump_errors" or "log4perl_dump_warnings" can be specified in "full_dump" parameter:

     full_dump => {
         log4perl_dump_warnings => [ ... ], # optional
         dump_errors            => [ ... ], # optional
  • Run specific content check to verify that configuration data was retrieved correctly:

        check => {
            'fs:/proc fs_spec' => "proc",
            'fs:/proc fs_file' => "/proc",
            'fs:/home fs_file' => "/home",

    The keys of the hash points to the value to be checked using the syntax described in "grab" in Config::Model::Role::Grab.

    Multiple check on the same item can be applied with a array ref:

        check => [
            Synopsis => 'fix undefined path_max for st_size zero',
            Description => [ qr/^The downstream/,  qr/yada yada/ ]

    You can run check using different check modes (See "fetch" in Config::Model::Value) by passing a hash ref instead of a scalar :

        check  => {
            'sections:debian packages:0' => { mode => 'layered', value => 'dpkg-dev' },
            'sections:base packages:0'   => { mode => 'layered', value => "gcc-4.2-base' },

    The whole hash content (except "value") is passed to grab and fetch

    A regexp can also be used to check value:

       check => {
          "License text" => qr/gnu/i,

    And specification can nest hash or array style:

       check => {
          "License:0 text" => qr/gnu/i,
          "License:1 text" => [ qr/gnu/i, qr/Stallman/ ],
          "License:2 text" => { mode => 'custom', value => [ qr/gnu/i , qr/Stallman/ ] },
          "License:3 text" => [ qr/General/], { mode => 'custom', value => [ qr/gnu/i , qr/Stallman/ ] },
  • Verify if a hash contains one or more keys (or keys matching a regexp):

     has_key => [
        'sections' => 'debian', # sections must point to a hash element
        'control' => [qw/source binary/],
        'copyright Files' => qr/.c$/,
        'copyright Files' => [qr/\.h$/], qr/\.c$/],
  • Verify that a hash does not have a key (or a key matching a regexp):

     has_not_key => [
        'copyright Files' => qr/.virus$/ # silly, isn't ?
  • Verify annotation extracted from the configuration file comments:

        verify_annotation => {
                'source Build-Depends' => "do NOT add libgtk2-perl to build-deps (see bug #554704)",
                'source Maintainer' => "what a fine\nteam this one is",
  • Write back the config data in "wr_root/model_tests/<subtest name>/". Note that write back is forced, so the tested configuration files are written back even if the configuration values were not changed during the test.

    You can skip warning when writing back with the global :

        no_warnings => 1,
  • Check the content of the written files(s) with Test::File::Contents. Tests can be grouped in an array ref:

       file_contents => {
                "/home/foo/my_arm.conf" => "really big string" ,
                "/home/bar/my_arm.conf" => [ "really big string" , "another"], ,
       file_contents_like => {
                "/home/foo/my_arm.conf" => [ qr/should be there/, qr/as well/ ] ,
       file_contents_unlike => {
                "/home/foo/my_arm.conf" => qr/should NOT be there/ ,
  • Check the mode of the written files:

      file_mode => {
         "~/.ssh/ssh_config"     => oct(600), # better than 0600
         "debian/stuff.postinst" => oct(755),

    Only the last four octets of the mode are tested. I.e. the test is done with " $file_mode & oct(7777) "

    Note: this test is skipped on Windows

  • Check added or removed configuration files. If you expect changes, specify a subref to alter the file list:

        file_check_sub => sub {
            my $list_ref = shift ;
            # file added during tests
            push @$list_ref, "/debian/source/format" ;

    Note that actual and expected file lists are sorted before check, adding a file can be done with "push".

  • Copy all config data from "wr_root/model_tests/<subtest name>/" to "wr_root/model_tests/<subtest name>-w/". This steps is necessary to check that configuration written back has the same content as the original configuration.
  • Create a second configuration instance to read the conf file that was just copied (configuration data is checked.)
  • You can skip the load check if the written file still contain errors (e.g. some errors were ignored and cannot be fixed) with "load_check2 => 'no'"
  • Optionally load configuration data in the second instance. You should design this config data to suppress any error or warning that occur in the step below. E.g:

        load2 => 'binary:seaview',

    See Config::Model::Loader for the syntax of the string accepted by "load2" parameter.

  • Compare data read from original data.
  • Run specific content check on the written config file to verify that configuration data was written and retrieved correctly:

        wr_check => {
            'fs:/proc fs_spec' =>          "proc" ,
            'fs:/proc fs_file' =>          "/proc",
            'fs:/home fs_file' =>          "/home",

    Like the "check" item explained above, you can run "wr_check" using different check modes.

Running the test

Run all tests with one of these commands:

 prove -l t/model_test.t :: [ --trace ] [ --log ] [ --error ] [ <model_name> [ <regexp> ]]
 perl -Ilib t/model_test.t  [ --trace ] [ --log ] [ --error ] [ <model_name> [ <regexp> ]]

By default, all tests are run on all models.

You can pass arguments to "t/model_test.t":

  • Optional parameters: "--trace" to get test traces. "--error" to get stack trace in case of errors, "--log" to have logs. E.g.

      # run with log and error traces
      prove -lv t/model_test.t :: --error --logl
  • The model name to tests. E.g.:

      # run only fstab tests
      prove -lv t/model_test.t :: fstab
  • A regexp to filter subtest E.g.:

      # run only fstab tests foobar subtest
      prove -lv t/model_test.t :: fstab foobar
      # run only fstab tests foo subtest
      prove -lv t/model_test.t :: fstab '^foo$'


Some of these examples may still use global variables (which is deprecated). Such files may be considered as buggy after Aug 2019. Please warn the author if you find one.


In alphabetical order:

Cyrille Bollu

Many thanks for your help.


  • Config::Model
  • Test::More


Dominique Dumont


This software is Copyright (c) 2013-2020 by Dominique Dumont.

This is free software, licensed under:

  The GNU Lesser General Public License, Version 2.1, February 1999



The following websites have more information about this module, and may be of help to you. As always, in addition to those websites please use your favorite search engine to discover more resources.

Bugs / Feature Requests

Please report any bugs or feature requests by email to "ddumont at", or through the web interface at <>. You will be automatically notified of any progress on the request by the system.

Source Code

The code is open to the world, and available for you to hack on. Please feel free to browse it and play with it, or whatever. If you want to contribute patches, please send me a diff or prod me to pull from your repository :)


  git clone git://
2021-10-30 perl v5.32.1