Cucumber Modules?

[cwellm]

@luke-hill

I saw that you filed an issue in The Cucumber C++ Repo and have been working on some of the Cucumber modules. I do not yet completely understand the relationship and meant usage of some parts. Could you have some words of clarification about it?

In particular, there are these two modules:

• Cucumber Messages
• Gherkin

which are both meant, among other things, to decouple the Gherkin language from Cucumber. First of all: What does "Cucumber" mean, in this context? Is it one of the fully implemented drivers, like in Ruby and JVM?

And then, what different goals do the abovementioned components have, and how can they play together?

Thanks very much in advance! :-)

[luke-hill]

So the cucumber cpp "flavour" (We call them flavours or other words to describe different languages using cucumber, such as java/javascript/ruby e.t.c), is a bit of a tricky beast. That is because it is an official version, but it is engineered slightly differently.

It is engineered to use a "wire" server. That is one that intercepts calls, and passes them based on it's interpretation. The wire server then uses the internals from cucumber-ruby.

https://github.com/cucumber/common is now just a documentation repo that explains the various moving parts. I can explain one example for one language.

Cucumber-Ruby is my example

• Cucumber-Ruby gem: Internals for working. It also contains delegation logic, as well as any formatting logic. It also contains all envelope generation (This generates the "letter" that we send as ndjson using our jsonschema).
• Cucumber-Ruby-Core: Unique to Ruby, but most languages have an equivalent - Complex internals allowing you to architect the inner hexagon of ruby. See here: https://github.com/cucumber/cucumber-ruby-core
• Cucumber-Expressions: Our library for translating nicer looking regex
• Cucumber-Messages: Our library for translating envelopes that pass messages. Mainly conversion / middleware
• Tag Expressions: Our library for some simple propositional logic for deciding which tags we want
• Cucumber-Query: Only javascript: This allows you to query gherkin
• Ci-Environment: A small helper library that obtains / translates some env variables when used in CI environments. Used to populate reports
• Cucumber-Html-Formatter: A shim library that wraps our javascript renderer for html reports. This decorates your cucumber run neatly when using --format html
• Cucumber-Gherkin: Our parser for gherkin. See the library here: https://github.com/cucumber/gherkin

Now you see how complex the internals of a cucumber implementation are, it might explain why pivoting from not using it's own internals to using it's own internals is no small feat.