Provide access to the testing.T log function in the context

[mrsheepuk]

🤔 What's changed?

Simply adding an interface over testing.T's log and logf functions to the context, allowing logging of information contextually. Vaguely related to #535 and #100 as, if this pattern is OK, it could be expanded to provide the whole of testing.T.

Example usage:

func log(ctx context.Context, msg string, args ...interface{}) {
    if t := godog.GetTestLogger(ctx); t != nil {
        t.Logf(msg, args...)
    } else {
        fmt.Println(fmt.Printf(msg, args...))
    }
}

⚡️ What's your motivation?

We have longer-running asynchronous tests which, when run, we want to provide contextual feedback to the user on during the execution. By using the sub-test's testing.T, these log messages appear in a sane place in the formatted output.

🏷️ What kind of change is this?

• :zap: New feature (non-breaking change which adds new behaviour)

♻️ Anything particular you want feedback on?

Opening this early for feedback - if it is conceptually sane, I'll work this PR up to a better state and add docs - didn't want to bother documenting it in detail if it's not going to be acceptable tho!

📋 Checklist:

• [x] I agree to respect and uphold the Cucumber Community Code of Conduct
• [ ] I've changed the behaviour of the code
  • [ ] I have added/updated tests to cover my changes.
• [x] My change requires a change to the documentation.
  • [ ] I have updated the documentation accordingly.
• [ ] Users should know about my change
  • [ ] I have added an entry to the "Unreleased" section of the CHANGELOG, linking to this pull request.

[tigh-latte]

I like this idea, but, the use of if and else to change between loggers makes me think we could improve the API.

Given that log/slog now has a few functions which take context.Context as their first param, perhaps we could follow suit and expose a few log functions in godog. So your example would be something like:

func log(ctx context.Context, msg string, args ...any) {
    godog.Logf(ctx, msg, args...)
}

Under the hood, that/(those?) functions would check if we have a logger in context.Context, and act accordingly:

func Logf(ctx context.Context, msg string, args ...any) {
    if logger := getLogger(ctx); logger != nil {
        logger.Logf(msg, args...)
    } else {
        fmt.Println(msg+"\n", args...)
    }
}

godog would then expose every function in testing.T that we are comfortable with exposing.

[mrsheepuk]

Ooooh, yes, I see what you mean @tigh-latte - I'll have a further play and see if I can come up with a pattern that also solves the testify/assert problem (as I also hit that) without breaking the fundamental way of working...

[mrsheepuk]

Superseded by #571 - @tigh-latte if you could take a look there and see if that's close to what you had in mind 😄