My apologies ahead of time if I'm overlooking the obvious, but I have not found any github or backdrop documentation that clarifies how to do this. I am looking at an issue, #2351. I was involved in the discussion but never tested the pull request because I never did figure out how to do it in the short amount of time I had over the last couple weeks. It shows, BWPanda added "status - has pull request" "pr - needs review" labels. A followup comment said "I gave this a quick spin in the PR sandbox...". So how does one do that? I clicked on the "pr - needs review" link and it takes me to the entire list of issues needing review. So I search for issue #2351 using the filters field and it only finds issue #2402. I went back and clicked on "status - has pull request". That takes me to the entire list of pull requests for all pr's. Again, a search for #2351, only finds issue #2402. OK. Back to the original issue page, https://github.com/backdrop/backdrop-issues/issues/2351 I try clicking the "Pull requests" tab at the top of the page. That only reveals 1 open issue, #3409, which does not appear to be related to this issue at all. I click the "5 closed" link. That does not find this issue either. On the https://backdropcms.org/contribute page, it says
we could use your help testing our work. Check the GitHub issue queue for issues that are tagged with needs review. There is a sandbox site created automatically for each PR, and we could use some help testing those sites for the intended changes.
But everything I try sends me either in circles or to dead ends. I would think that the "has pull request" or the "pr - needs review" link would take me directly to the sandbox for testing. Or, at least, take me to the repository page with a link to download the code for testing. After going in circles for a while, I finally noticed a link posted on the #2351 pr page to yet another pr, #2388. I clicked on that one, yet still no links anywhere to take me to a sandbox site for testing.
This is a good question. In the example you used, you should find the actual pull request in the discussion thread.
If you click on the pull request, it will take you here:
https://github.com/backdrop/backdrop/pull/2388
On this issue, you will find a link to a sandbox along with login credentials.
This should work for most core issues, but personally I've been trying to figure out the best way to test contrib pull requests (I have not yet looked very hard).
Better or easier to find documentation would be helpful.
Summary: