fix: generate multipage TOC with http_prefix

[lhokktyn]

Please see replication steps here: alphagov/tech-docs-template#183 (comment)

Whilst the test already in place appears to work, I'm not sure it is covering my particular case because when I build my site it is not generating files within a prefixed folder, so I may need a bit of guidance to write additional test (or correct my approach!) ...

For example, when http_prefix=/prefix/, given my source/:

|- source/
|--documentation/
|--index.html.md.erb
|--page2.html.md.erb

This is generating files in the build directory as so:

|- build/
|--index.html
|--page2.html

But the test in place appears to expect generated assets to be:

|- build/
|--prefix/index.html
|--prefix/page2.html

The attached PR does fix the issue for me, however.

[NickColley]

Hello @lhokktyn,

Do you have time to finish this work in progress up, or should we close this for now (and consider raising a bug report instead)?

[lhokktyn]

Hi @NickColley , apologies for the very tardy reply!

I've been using this fix locally for a few months and it works for our use case, but as I'm an amateur Rubyer and my experience with the tech docs gem is very light touch, I was hoping someone more experienced in these matter might be free to review this fix and test if it'll apply correctly in more common usage scenarios.

Cheers

[djn72]

Is there any movement on this?

We have multiple teams/projects relying on this fork/fix to build docs within GitLab Pages and it'd be great to see this included so we can tidy up and use a tagged version from the official repo :-)

[edjannoo]

I'd like to add my voice to getting this resolved in the main codebase. At HMRC we're building rich content guides that are hosted within the Developer Hub and therefore are deployed under a custom path prefix. We've had to override the multi_page_table_of_contents function in our local config.rb with the code from this PR (thanks @lhokktyn!) to make this work.

[odlp]

We'd also benefit from this fix over on the API catalogue. Please let me know if I can be of any assistance.

[TomTucka]

Any idea when this will be merged? Causing us some issues over at MoJ

[odlp]

@TomTucka I can't speak to when this will be merged, but I did create a http-prefix-support branch in this repo which combines this PR + #196 + #197 which are other http_prefix related fixes. It can be sourced like this:

gem "govuk_tech_docs", git: "https://github.com/alphagov/tech-docs-gem.git", branch: "http-prefix-support"

[huwd]

this is a v4 candidate, seems useful and small enough to review (@lhokktyn - sincere apologies you've had to wait so long, there's a group of us trying to return to do a stint of maintenance here) - I'll try and review properly this week.

[marcotranchino]

We could potentially extract an helper method:

def determine_home_url(http_prefix)
  http_prefix.end_with?("/") ? http_prefix : "#{http_prefix}/"
end

And then within multi_page_table_of_contents we could use it:

home_url = determine_home_url(config[:http_prefix])

[marcotranchino]

I have made a small optional suggestion, but anyway this LGTM 👍