Gherkin Reference¶
Gherkin uses a set of special keywords to give structure and meaning to executable specifications. Each keyword is translated to many spoken languages; in this reference we’ll use English.
Most lines in a Gherkin document start with one of the keywords.
Comments are only permitted at the start of a new line, anywhere in the feature file. They begin with zero or more spaces,
followed by a hash sign (#) and some text.
Block comments are currently not supported by Gherkin.
Either spaces or tabs may be used for indentation. The recommended indentation level is two spaces. Here is an example:
Feature: Guess the word
# The first example has two steps
Scenario: Maker starts a game
When the Maker starts a game
Then the Maker waits for a Breaker to join
# The second example has three steps
Scenario: Breaker joins a game
Given the Maker has started a game with the word "silky"
When the Breaker joins the Maker's game
Then the Breaker must guess a word with 5 characters
The trailing portion (after the keyword) of each step is matched to a code block, called a step definition.
Keywords¶
Each line that isn’t a blank line has to start with a Gherkin keyword, followed by any text you like. The only exceptions are the feature and scenario descriptions.
The primary keywords are:
FeatureRule(as of Gherkin 6)Example(orScenario)Given,When,Then,And,Butfor steps (or*)BackgroundScenario Outline(orScenario Template)Examples
There are a few secondary keywords as well:
"""(Doc Strings)|(Data Tables)@(Tags)#(Comments)
Localisation Gherkin is localised for many spoken languages; each has their own localised equivalent of these keywords.
Feature¶
The purpose of the Feature keyword is to provide a high-level description
of a software feature, and to group related scenarios.
The first primary keyword in a Gherkin document must always be Feature, followed
by a : and a short text that describes the feature.
You can add free-form text underneath Feature to add more description.
These description lines are ignored by SpecFlow at runtime, but are available for reporting (They are included by default in html reports).
Feature: Guess the word
The word guess game is a turn-based game for two players.
The Maker makes a word for the Breaker to guess. The game
is over when the Breaker guesses the Maker's word.
Scenario: Maker starts a game
The name and the optional description have no special meaning to SpecFlow. Their purpose is to provide a place for you to document important aspects of the feature, such as a brief explanation and a list of business rules (general acceptance criteria).
The free format description for Feature ends when you start a line with the keyword Background, Rule, Example or Scenario Outline (or their alias keywords).
You can place tags above Feature to group related features, independent of your file and directory structure.
Descriptions¶
Free-form descriptions (as described above for Feature) can also be placed underneath
Example/Scenario, Background, Scenario Outline and Rule.
You can write anything you like, as long as no line starts with a keyword.
Rule¶
The (optional) Rule keyword has been part of Gherkin since v6.
Support in SpecFlow
To be able to work with rules in Visual Studio, you have to use Visual Studio 2022 or use the “Deveroom” extension for Visual Studio 2017 and 2019. Otherwise the syntax highlighting will be broken.
The purpose of the Rule keyword is to represent one business rule that should be implemented.
It provides additional information for a feature.
A Rule is used to group together several scenarios
that belong to this business rule. A Rule should contain one or more scenarios that illustrate the particular rule.
From SpecFlow v4, you can also add tags on rules that will be inherited to all scenarios within that rule (like feature tags).
For example:
# -- FILE: features/gherkin.rule_example.feature
Feature: Highlander
Rule: There can be only One
Scenario: Only One -- More than one alive
Given there are 3 ninjas
And there are more than one ninja alive
When 2 ninjas meet, they will fight
Then one ninja dies (but not me)
And there is one ninja less alive
Scenario: Only One -- One alive
Given there is only 1 ninja alive
Then he (or she) will live forever ;-)
@edge_case
Rule: There can be Two (in some cases)
Scenario: Two -- Dead and Reborn as Phoenix
...
Scenario¶
This is a concrete example that illustrates a business rule. It consists of a list of steps.
The keyword Scenario is a synonym of the keyword Example.
You can have as many steps as you like, but we recommend you keep the number at 3-5 per example. Having too many steps in an example, will cause it to lose it’s expressive power as specification and documentation.
In addition to being a specification and documentation, an example is also a test. As a whole, your examples are an executable specification of the system.
Examples follow this same pattern:
Describe an initial context (
Givensteps)Describe an event (
Whensteps)Describe an expected outcome (
Thensteps)
Steps¶
Each step starts with Given, When, Then, And, or But.
SpecFlow executes each step in a scenario one at a time, in the sequence you’ve written them in. When SpecFlow tries to execute a step, it looks for a matching step definition to execute.
Keywords are not taken into account when looking for a step definition. This means you cannot have a
Given, When, Then, And or But step with the same text as another step.
SpecFlow considers the following steps duplicates:
Given there is money in my account
Then there is money in my account
This might seem like a limitation, but it forces you to come up with a less ambiguous, more clear domain language:
Given my account has a balance of £430
Then my account should have a balance of £430
Given¶
Given steps are used to describe the initial context of the system - the scene of the scenario.
It is typically something that happened in the past.
When SpecFlow executes a Given step, it will configure the system to be in a well-defined state,
such as creating and configuring objects or adding data to a test database.
The purpose of Given steps is to put the system in a known state before the user (or external system) starts interacting with the system (in the When steps).
Avoid talking about user interaction in Given’s. If you were creating use cases, Given’s would be your preconditions.
It’s okay to have several Given steps (use And or But for number 2 and upwards to make it more readable).
Examples:
Mickey and Minnie have started a game
I am logged in
Joe has a balance of £42
When¶
When steps are used to describe an event, or an action. This can be a person interacting with the system, or it can be an event triggered by another system.
It’s strongly recommended you only have a single When step per Scenario. If you feel compelled to add more, it’s usually a sign that you should split the scenario up into multiple scenarios.
Examples:
Guess a word
Invite a friend
Withdraw money
Imagine it’s 1922 Most software does something people could do manually (just not as efficiently).
Try hard to come up with examples that don’t make any assumptions about technology or user interface. Imagine it’s 1922, when there were no computers.
Implementation details should be hidden in the step definitions.
Then¶
Then steps are used to describe an expected outcome, or result.
The step definition of a Then step should use an assertion to
compare the actual outcome (what the system actually does) to the expected outcome
(what the step says the system is supposed to do).
An outcome should be on an observable output. That is, something that comes out of the system (report, user interface, message), and not a behavior deeply buried inside the system (like a record in a database).
Examples:
See that the guessed word was wrong
Receive an invitation
Card should be swallowed
While it might be tempting to implement Then steps to look in the database - resist that temptation!
You should only verify an outcome that is observable for the user (or external system), and changes to a database are usually not.
And, But¶
If you have successive Given’s, When’s, or Then’s, you could write:
Scenario: Multiple Givens
Given one thing
Given another thing
Given yet another thing
When I open my eyes
Then I should see something
Then I shouldn't see something else
Or, you could make the example more fluidly structured by replacing the successive Given’s, When’s, or Then’s with And’s and But’s:
Scenario: Multiple Givens
Given one thing
And another thing
And yet another thing
When I open my eyes
Then I should see something
But I shouldn't see something else
*¶
Gherkin also supports using an asterisk (*) in place of any of the normal step keywords. This can be helpful when you have some steps that are effectively a list of things, so you can express it more like bullet points where otherwise the natural language of And etc might not read so elegantly.
For example:
Scenario: All done
Given I am out shopping
And I have eggs
And I have milk
And I have butter
When I check my list
Then I don't need anything
Could be expressed as:
Scenario: All done
Given I am out shopping
* I have eggs
* I have milk
* I have butter
When I check my list
Then I don't need anything
Background¶
Occasionally you’ll find yourself repeating the same Given steps in all of the scenarios in a Feature.
Since it is repeated in every scenario, this is an indication that those steps
are not essential to describe the scenarios; they are incidental details. You can literally move such Given steps to the background, by grouping them under a Background section.
A Background allows you to add some context to the scenarios that follow it. It can contain one or more Given steps, which are run before each scenario, but after any Before hooks.
A Background is placed before the first Scenario/Example, at the same level of indentation.
For example:
Feature: Multiple site support
Only blog owners can post to a blog, except administrators,
who can post to all blogs.
Background:
Given a global administrator named "Greg"
And a blog named "Greg's anti-tax rants"
And a customer named "Dr. Bill"
And a blog named "Expensive Therapy" owned by "Dr. Bill"
Scenario: Dr. Bill posts to his own blog
Given I am logged in as Dr. Bill
When I try to post to "Expensive Therapy"
Then I should see "Your article was published."
Scenario: Dr. Bill tries to post to somebody else's blog, and fails
Given I am logged in as Dr. Bill
When I try to post to "Greg's anti-tax rants"
Then I should see "Hey! That's not your blog!"
Scenario: Greg posts to a client's blog
Given I am logged in as Greg
When I try to post to "Expensive Therapy"
Then I should see "Your article was published."
For a less explicit alternative to Background, check out scoped step definitions.
Tips for using Background¶
Don’t use
Backgroundto set up complicated states, unless that state is actually something the client needs to know.For example, if the user and site names don’t matter to the client, use a higher-level step such as
Given I am logged in as a site owner.
Keep your
Backgroundsection short.The client needs to actually remember this stuff when reading the scenarios. If the
Backgroundis more than 4 lines long, consider moving some of the irrelevant details into higher-level steps.
Make your
Backgroundsection vivid.Use colourful names, and try to tell a story. The human brain keeps track of stories much better than it keeps track of names like
"User A","User B","Site 1", and so on.
Keep your scenarios short, and don’t have too many.
If the
Backgroundsection has scrolled off the screen, the reader no longer has a full overview of whats happening. Think about using higher-level steps, or splitting the*.featurefile.
Scenario Outline¶
The Scenario Outline keyword can be used to run the same Scenario multiple times,
with different combinations of values.
The keyword Scenario Template is a synonym of the keyword Scenario Outline.
Copying and pasting scenarios to use different values quickly becomes tedious and repetitive:
Scenario: eat 5 out of 12
Given there are 12 cucumbers
When I eat 5 cucumbers
Then I should have 7 cucumbers
Scenario: eat 5 out of 20
Given there are 20 cucumbers
When I eat 5 cucumbers
Then I should have 15 cucumbers
We can collapse these two similar scenarios into a Scenario Outline.
Scenario outlines allow us to more concisely express these scenarios through the use
of a template with < >-delimited parameters:
Scenario Outline: eating
Given there are <start> cucumbers
When I eat <eat> cucumbers
Then I should have <left> cucumbers
Examples:
| start | eat | left |
| 12 | 5 | 7 |
| 20 | 5 | 15 |
A Scenario Outline must contain an Examples (or Scenarios) section. Its steps are interpreted as a template
which is never directly run. Instead, the Scenario Outline is run once for each row in
the Examples section beneath it (not counting the first header row).
The steps can use <> delimited parameters that reference headers in the examples table.
SpecFlow will replace these parameters with values from the table before it tries
to match the step against a step definition.
> Note: Tables used in Examples must have unique headers. Using duplicate headers will result in errors.
Hint: In certain cases, when generating method names using the regular expression method, SpecFlow is unable to generate the correct parameter signatures for unit test logic methods without a little help. Placing single quotation marks (') around placeholders (eg. '<placeholder>')improves SpecFlow’s ability to parse the scenario outline and generate more accurate regular expressions and test method signatures.
You can also use parameters in multiline step arguments.
Step Arguments¶
In some cases you might want to pass more data to a step than fits on a single line.
For this purpose Gherkin has Doc Strings and Data Tables.
Doc Strings¶
Doc Strings are handy for passing a larger piece of text to a step definition.
The text should be offset by delimiters consisting of three double-quote marks on lines of their own:
Given a blog post named "Random" with Markdown body
"""
Some Title, Eh?
===============
Here is the first paragraph of my blog post. Lorem ipsum dolor sit amet,
consectetur adipiscing elit.
"""
In your step definition, there’s no need to find this text and match it in your pattern. It will automatically be passed as the last argument in the step definition.
Indentation of the opening """ is unimportant, although common practice is two spaces in from the enclosing step.
The indentation inside the triple quotes, however, is significant. Each line of the Doc String will be dedented according to the opening """. Indentation beyond the column of the opening “”” will therefore be preserved.
Data Tables¶
Data Tables are handy for passing a list of values to a step definition:
Given the following users exist:
| name | email | twitter |
| Aslak | [email protected] | @aslak_hellesoy |
| Julien | [email protected] | @jbpros |
| Matt | [email protected] | @mattwynne |
Just like Doc Strings, Data Tables will be passed to the step definition as the first argument.
SpecFlow provides a rich API for manipulating tables from within step definitions. See the Assist Namespace reference for more details.
Markdown¶
You can include markdown code in your feature files with the standard Markdown features such as bold, italic, lists etc. This is useful when generating documentation via the SpecFlow+ LivingDoc generator.
Click here to find out more.
Spoken Languages¶
The language you choose for Gherkin should be the same language your users and domain experts use when they talk about the domain. Translating between two languages should be avoided.
This is why Gherkin has been translated to over 70 languages.
Here is a Gherkin scenario written in Norwegian:
# language: no
Funksjonalitet: Gjett et ord
Eksempel: Ordmaker starter et spill
Når Ordmaker starter et spill
Så må Ordmaker vente på at Gjetter blir med
Eksempel: Gjetter blir med
Gitt at Ordmaker har startet et spill med ordet "bløtt"
Når Gjetter blir med på Ordmakers spill
Så må Gjetter gjette et ord på 5 bokstaver
A # language: header on the first line of a feature file tells SpecFlow what
spoken language to use - for example # language: fr for French.
If you omit this header, SpecFlow will default to English (en).
You can also define the language in the configuration file.
Gherkin Dialects¶
In order to allow Gherkin to be written in a number of languages, the keywords have been translated into multiple languages. To improve readability and flow, some languages may have more than one translation for any given keyword.
Overview¶
You can find all translation of Gherkin on GitHub. This is also the place to add or update translations.
Note Big parts of this page where taken over from https://cucumber.io/docs/gherkin/reference/.