Provided by: libtest-bdd-cucumber-perl_0.82-1_all 
NAME
Test::BDD::Cucumber::Manual::Steps - How to write Step Definitions
VERSION
version 0.82
INTRODUCTION
The 'code' part of a Cucumber test-suite are the Step Definition files which match steps,
and execute code based on them. This document aims to give you a quick overview of those.
STARTING OFF
Most of your step files will want to start something like:
#!perl
package my_step_functions_for_feature_X;
use strict;
use warnings;
use Test::More; # 'use Test2::V0;' is also supported
use Test::BDD::Cucumber::StepFile;
The fake shebang line gives some hints to syntax highlighters, and "use strict;" and "use
warnings;" are hopefully fairly standard at this point.
Most of my Step Definition files make use of Test::More, but you can use any Test2 or
Test::Builder based testing module. E.g. "Test2::V0" or "Test::Exception".
Test::BDD::Cucumber::StepFile gives us the functions "Given()", "When()", "Then()" and
"Step()".
STEP DEFINITIONS
Given qr/I have (\d+)/, sub {
S->{'count'} += $1;
};
When "The count is an integer", sub {
S->{'count'} =
int( S->{'count'} );
};
Then qr/The count should be (\d+)/, sub {
is( S->{'count'}, C->matches->[0], "Count matches" );
};
Each of the exported verb functions accept a regular expression (or a string that's used
as one), and a coderef. The coderef is passed a single argument, the
Test::BDD::Cucumber::StepContext object. Before the subref is executed, localized
definitions of "S" and "C" are set, such that the lines below are equivalent:
# Access the first match
sub { my $context = shift; print $context->matches->[0] }
sub { C->matches->[0] }
# Set a value in the scenario-level stash
sub { my $context = shift; my $stash = $context->stash->{'scenario'}; $stash->{'count'} = 1 }
sub { S->{'count'} = 1 }
We will evaluate the regex immediately before we execute the coderef, so you can use $1,
$2, $etc. Similarly you can access named matches using $+{match_name}.
Accessing step, scenario and feature properties
Step functions have access to the various properties of the step, scenario and feature in
which they're being used. This includes tags, line numbers, etc. E.g.:
# Examples of step properties
C->step->line->number
C->step->verb
C->step->original_verb
# Examples of scenario properties
C->scenario->name
C->scenario->tags
# Examples of feature properties
C->feature->name
C->feature->tags
C->feature->language
For a full review of available properties, see Test::BDD::Cucumber::Model::Step,
Test::BDD::Cucumber::Model::Scenario and Test::BDD::Cucumber::Model::Feature respectively.
Re-using step definitions
Sometimes you want to call one step from another step. You can do this via the
StepContext, using the "dispatch()" method. For example:
Given qr/I have entered (\d+)/, sub {
C->dispatch( 'Given', "I have pressed $1");
C->dispatch( 'Given', "I have pressed enter", { some => 'data' } );
};
For more on this topic, check the Redispatching section in the documentation for
"Test::BDD::Cucumber::StepContext".
LOCALIZATION
Both feature files and step files can be written using non-english Gherkin keywords. A
german feature file could look like the example below.
# language: de
Funktionalität: Grundlegende Taschenrechnerfunktionen
Um sicherzustellen, dass ich die Calculator-Klasse korrekt programmiert habe,
möchte ich als Entwickler einige grundlegende Funktionen prüfen,
damit ich beruhigt meine Calculator-Klasse verwenden kann.
Szenario: Anzeige des ersten Tastendrucks
Gegeben sei ein neues Objekt der Klasse Calculator
Wenn ich 1 gedrückt habe
Dann ist auf der Anzeige 1 zu sehen
To see which keywords (and sub names) to use, ask pherkin about a specific language:
> pherkin --i18n de
| feature | "Funktionalität" |
| background | "Grundlage" |
...
| given (code) | "Angenommen", "Gegebensei", "Gegebenseien" |
| when (code) | "Wenn" |
| then (code) | "Dann" |
The last three lines of this list show you which sub names to use in your step file as
indicated by the '(code)' suffix. A corresponding step file specifying a step function for
"Wenn ich 1 gedrückt habe", could be:
#!perl
use strict;
use warnings;
use utf8; # Interpret accented German chars in regexes and identifiers properly
use Test::More;
use Test::BDD::Cucumber::StepFile;
Wenn qr/^ich (.+) gedrückt habe/, sub {
S->{'Calculator'}->press($_) for split( /(,| und) /, C->matches->[0] );
};
For more extensive examples see examples/i18n_de/ and examples/i18n_es.
ADDITIONAL STEPS
Next to the steps that will be matched directly against feature file input, a number of
additional step functions are supported:
• "Before" and "After"
These steps create hooks into the evaluation process of feature files. E.g.
Before sub { # Run before every scenario
# ... scenario set up code
};
After sub { # Run after every scenario
# ... scenario tear down code
};
For more extensive hook functionality, see Test::BDD::Cucumber::Extension.
• "Transform"
The "Transform" step serves to map matched values or table rows from feature file
(string) input to step input values. The step takes two arguments, same as the
"Given", "When" and "Then" steps: a regular expression and a code reference. E.g.
Transform qr/^(\d+)$/, sub {
# transform matches of digit-only strings
my $rv = $1;
# ... do something with $rv
return $rv;
};
Transform qr/^table:col1,col2$/, sub {
# transform tables with 2 columns, named col1 and col2 respectively
my ($step_context, $data) = @_;
# ... transform data in $data
return $data;
};
BEST PRACTICES
When writing step files, it's a good idea to take a few things into account.
• Declare a "package" at the top of your step file
By declaring a specific package (your own), you make sure not to step on internals of
other modules. At the time of writing, the default package is
"Test::BDD::Cucumber::StepFile", which may lead to errors being reported in that
package, even though they occur in your step file (which is confusing).
The default package may change in the future and it will likely not be seeded with the
content of the "T::B::C::StepFile" package.
• Declare a different "package" per step file
By using different packages per step file (or group of step files), name spaces are
isolated which reduces the risk of importing functions with the same name from
different packages.
An example where this will be the case is when some of your step files are written
using "Test::More" and some others are written using "Test2::Bundle::More" -- both
export a function "ok", but with conflicting function prototypes.
• Don't define functions in your step file
Especially step files provided by extensions. Step files may be loaded more than once,
depending on the exact scenario in which "App::pherkin" is run. When the step files
are being loaded multiple times, there won't be any impact on step definition, but any
function definitions will cause 'function redefined' warnings.
NEXT STEPS
How step files are loaded is discussed in Test::BDD::Cucumber::Manual::Architecture, but
isn't of much interest. Of far more interest should be seeing what you have available in
Test::BDD::Cucumber::StepContext...
AUTHOR
Peter Sergeant "pete@clueball.com"
LICENSE
Copyright 2019-2021, Erik Huelsmann
Copyright 2011-2019, Peter Sergeant; Licensed under the same terms as Perl