Connections no longer return all items when the "before" argument is the first cursor

[d-arrington]

Problem

Consider the following request and response:

query {
  animals (first: 5, before: null) {
    edges {
      cursor
    }
  }
}

{
  "data": {
    "animals": {
      "edges": [
        { "cursor": "1" },
        { "cursor": "2" },
        { "cursor": "3" },
        { "cursor": "4" },
        { "cursor": "5" }
      ]
    }
  }
}

What if we pass in a before cursor that's equal to the first item? We get this:

query {
  animals (first: 5, before: "1") {
    edges {
      cursor
    }
  }
}

{
  "data": {
    "animals": {
      "edges": [
        { "cursor": "1" },
        { "cursor": "2" },
        { "cursor": "3" },
        { "cursor": "4" },
        { "cursor": "5" }
      ]
    }
  }
}

That's not correct. Those edges are not before the first edge. The actual response should be this:

{
  "data": {
    "animals": {
      "edges": []
    }
  }
}

Cause

The calculation for the range of nodes that should be loaded is items[0..index_from_cursor(before)-2] || []. So if the before cursor is the first cursor, then the node range becomes [0..-1], encompassing all items in the list.

[rmosolgo]

Thanks for the fix on this! It looks like an existing test or two was broken, do you mind looking into it?

[d-arrington]

And that's why we have tests! It was a silly typo, but it's been fixed.

[rmosolgo]

✨ Thanks!