Replace the generic Step function with Given/When/Then functions to match the majority of other languages

[mirogta]

🤔 What's the problem you're trying to solve?

I'm trying to add support for Go (godog) to Cucumber language service, so that we can finally use Go BDD support in VSCode.

It's a bit tricky because of the generic Step func and not having the separate Given/When/Then funcs instead.

Raised a poll here: #542

✨ What's your proposed solution?

• Mark the Step function as deprecated
• Add 3 new functions to match their respective counterparts in the feature files - Given/When/Then

⛏ Have you considered any alternatives or workarounds?

No alternatives considered. I think we should "just" do this to keep the syntax consistent with other programming languages.

📚 Any additional context?

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[otrava7]

Hello @mirogta,
One thing to note is we have already introduced Given/When/Then functions as part of: #509
The above is not released yet, but the functions will be available once released. The Step function is not deprecated at this point though.

[mirogta]

Looking at

godog/test_context.go

Line 261 in bcffb1c

func (ctx *ScenarioContext) Given(expr, stepFunc interface{}) {

, there are already funcs Given/When/Then. So we can perhaps mark the "preferred" Step func as obsolete.

Concern about terminology:
The hooks BeforeStep and AfterStep should stay. Assuming these can be explained in the docs, as in Given/When/Then are the actual funcs and Step is just their abstraction.

[mirogta]

@otrava7 thanks - yeah, found it as well now.

I'm looking at this more holistically, i.e. can we also replace the generic Step everywhere else, in the snippets, in the documentation & examples etc.

[otrava7]

That makes sense to me!

[seanw2020]

On a related note, the docs say, at https://github.com/cucumber/godog:

Alternatively, you can also specify the keyword (Given, When, Then...) when creating the step definitions:

But that doesn't work when go.mod says require github.com/cucumber/godog v0.12.6 because you get this instead:

./godogs_test.go:18:6: ctx.Given undefined (type *godog.ScenarioContext has no field or method Given)

[vearutop]

@seanw2020 Recent changes have not been released as a tagged version yet, however you can go ahead and upgrade to latest main by go get -u github.com/cucumber/godog@main.

[otrava7]

I'm keen to start working on this. Just checking that no one has started already

[mirogta]

@otrava7 that's great! I've started looking into it to understand the scope and effort a bit more, but very happy for someone else to actually deliver it. Hope the (WIP) branch above helps.

[otrava7]

That's more or less what I was planning to do as well, is there anything else you were looking to do?

[mirogta]

That's more or less what I was planning to do as well, is there anything else you were looking to do?

No, that's it.

Observations:

• There are tests for the Step definition having different meaning: Given/When/Then. Does it actually make sense? That made it a bit difficult to choose which keyword should the Step be replaced with, but I've made the best guesses. Should it even be allowed? E.g. if I have an assert (Then) then how would it make sense to use it in arrangement (Given)?
• There's a single template for the code snippets for all Given/When/Then - it might need to be split to give more flexibility and potentially allow configuring custom snippets.
• There's also a single slice for all runtime steps - probably makes sense to keep it and still continue to refer to all Given/When/Then as a Step abstraction.
• Not for this ticket, but Makefile didn't work OOB for me = more effort to contribute. Can we make it more flexible so it's easier to use with multiple installed versions of Go? It doesn't seem like a good idea to assume everyone has the required Go version, esp. when it's not the latest stable.

[otrava7]

There are tests for the Step definition having different meaning: Given/When/Then. Does it actually make sense? That made it a bit difficult to choose which keyword should the Step be replaced with, but I've made the best guesses. Should it even be allowed? E.g. if I have an assert (Then) then how would it make sense to use it in arrangement (Given)?

Could you give an example for this? The Given()/When()/Then() functions are built to only match their respective keyword in the feature files. With the Step() function, it could match no matter the keyword.

[soulcodex]

@mirogta One question, Given and When with this approach will match and understand the And too? For example:

Given 2 ducks and one hunter 
And the hunter is ready for the action -> This will still matching regardless Given, When or Then ?
When the hunter shoots one time
Then "1" ducks left alive

[crosscode-nl]

Hi all, I created a PR that allows us to select a different snippet function for generating missing steps. The two options are now:

• steps_func
• gwt_func

steps_func is the default and old behaviour, gwt_func is a new function that generates the steps with the Given/When/Then keywords

I intend to add more snippet functions if this PR is merged.

For example: I personally would like the functions to be prefixed with the given/when/then keyword as well since Go does not use attributes. Also, I often work with methods on a TestFixture struct.

With this PR people can add snippet functions that match their workflow best.