Support the Rule keyword

[ciaranmcnulty]

This is new in Gherkin v6

https://docs.cucumber.io/gherkin/reference/#rule

[stof]

If we want to support it, we should also consider refactoring Behat and Gherkin to separate the Gherkin AST from what they call pickles. This way, the Behat runner would not have to know about the extra grouping features of the Gherkin syntax.
This would be a BC break for hooks (some hooks would have to disappear, as the execution itself would not know about outlines or backgrounds anymore for instance). This would be a BC break for Behat events (used among other things by formatters), not for hooks.

In any case, adding that would require a new behat/gherkin major version, as adding rules inside features would break Behat when running them.

[ciaranmcnulty]

Yes, if we went that route it might make sense to semi-generate the parser the same way that's done in other languages (and this repo might become a compat later)

Or cucumber-engine will become the future and we won't need a Gherkin parser for behat...

[stof]

Well, what other languages are doing is not semi-generating the parser. They are calling the go parser (as a CLI) and then only rebuilding the output objects. I'm not sure that's what we want for now.

[ciaranmcnulty]

I caught up about cucumber-engine and it looks like the future of it is uncertain (the idea was to have a large part of the runtime distributed as a binary).

I'll take a look at how disruptive adding Rule would be, and see if there are any other changes in Gherkin - maybe doing #95 is the best starting point?

[benztest]

I was wondering if there was any further updates regarding the Rule keyword?

As in my recent attempt to include two rules in a single feature results in an error.

  [Behat\Gherkin\Exception\ParserException]
  Expected Step, but got text: "Rule: Authenticate as a learner" in file: C:\<path>\<file>.feature

.feature:

Feature: ...

Rule: Rule: Do no authenticate

Scenario: ...

Scenario: ...

Rule: Rule: Authenticate as a learner

Scenario: ...

Scenario: ...

[ciaranmcnulty]

Uncommenting these lines will now produce a failing test for the Rule keyword implementation

https://github.com/Behat/Gherkin/blob/master/tests/Behat/Gherkin/Cucumber/CompatibilityTest.php#L29-L30
https://github.com/Behat/Gherkin/blob/master/tests/Behat/Gherkin/Cucumber/CompatibilityTest.php#L38

[Harrisonbro]

Sorry if this should be obvious, but is there somewhere we can see how support for the Rule keyword moves from this issue into a version of Behat we can use as end users? Sorry, I’m not familiar enough with the project or how open source works to figure this out myself.

[ciaranmcnulty]

This isn’t yet implemented here. Once it is, a new version of Behat will need to add support