package Test::BDD::Cucumber::Manual::Architecture;

=head1 NAME

Test::BDD::Cucumber::Manual::Architecture - Structural Overview

=head1 VERSION

version 0.72

=head1 INTRODUCTION

This short document exists to give you an idea how the different components of
this distribution fit together. Components fall into three categories: one for
dealing with definition of the step functions (Perl code), the other for dealing
with feature files. And then there's the third group, with
C<Test::BDD::Cucumber::Executor> which links the two groups together; building on
the steps to execute the features.

In the first group are C<Test::BDD::Cucumber::StepFile> and
C<Test::BDD::Cucumber::Loader>. The second group is bigger and is comprised of

=over 4

=item * C<Test::BDD::Cucumber::Parser>

=item * C<Test::BDD::Cucumber::Model::*>

=back

The third group holds - next to C<Test::BDD::Cucumber::Executor>:

=over 4

=item * C<Test::BDD::Cucumber::Harness::*>

=item * C<Test::BDD::Cucumber::StepContext>

=item * C<Test::BDD::Cucumber::Errors>

=item * C<Test::BDD::Cucumber::Extension>

=back

Please note that the C<Test::BDD::Cucumber::Harness> should not be confused
with C<TAP::Harness> or C<Test2::Harness>; this harness is TBC's own and
optionally forwards events to the C<Test::Builder::Test> harness.


=head1 MODELS

The core of a Cucumber-based test suite are the feature files and the step
definitions files. By convention, these are saved under C</features/> and
C</features/step_definitions/> respectively.

The feature files are encapsulated by the classes in
C<Test::BDD::Cucumber::Model>.

                  one to one
 TBCM::Feature<----------------->TBCM::Document
      |                               |
      +-------------------+           |
      | has many          | has a     | has many
      V                   |           V
 TBCM::Scenario           +----->TBCM::Line
      |                            ^  ^
      +----------------------------+  |
      | has many                      |
      V                               |
 TBCM::Step---------------------------+

=head1 EXECUTOR

We build up a L<Test::BDD::Cucumber::Executor> object, in to which we load the
step definitions. We then pass this in a L<Test::BDD::Cucumber::Model::Feature>
object, along with a L<Test::BDD::Cucumber::Harness> object, which
controls interaction with the outside world.

=head2 Test::Builder

While running step functions, C<Test::BDD::Cucumber::Executor> reroutes
the flow of test events (calls to C<ok>, C<fail>, etc) to itself. Based on the
collected data, the step itself is reported as a success or failure to the
test driver.

Confusing about this situation is that both the channel to report through to
the actual test driver is an instance of Test::Builder as well as the method
used to route the stream of test events to itself uses a Test::Builder instance.


=head1 EXTENSION

Extensions allow hooking into the execution of the steps, with pre- and post
hooks for steps, scenarios, features and the entire execution. Extensions
can provide additional step directories from which steps will be made
available. The feature and scenario stashes are passed to the extension hooks
allowing for a means of communication between the hooks and the steps.

Additionally, as of I<0.60>, it's possible to define meta data for a step
upon step definition like this example:

  Given qr/a step with meta data/ => { meta => 'data' }, sub { };

This allows step function authors to communicate with extensions, because
extensions receive this meta data in their C<pre_step> callback:

  sub pre_step {
    my ($step_function, $step_context) = @_;
    my $step_metadata = $step->[1];

    die 'All steps should have meta -> data'
      unless $step_metadata->{meta} eq 'data';
  }

Extensions - when loaded by the pherkin test executor - receive their
configuration from the pherkin.yaml configuration file, which works
similar to L<the configuration of extensions in
Behat|http://docs.behat.org/en/v2.5/guides/7.config.html#extensions>.

Note: when using extensions in combination with the
C<TAP::Parser::SourceHandler::Feature> plugin for C<prove>, there is no
guarantee that the C<pre_execute> and C<post_execute> hooks execute
exactly once or even execute at all.
This is a current limitation to be lifted in a future release.

=head1 AUTHOR

Peter Sergeant C<pete@clueball.com>

=head1 LICENSE

  Copyright 2019-2020, Erik Huelsmann
  Copyright 2011-2019, Peter Sergeant; Licensed under the same terms as Perl

=cut

1;
