Improve validation of needs output object

[Bertg]

Given the following workflow file:

name: Simplified CI example

on: [push]

jobs:
  detect_changes:
    name: "🔎 Detect Changes"
    runs-on: ubuntu-latest
    # outputs will always be strings
    outputs:
      graph: ${{ steps.graph_changes.outputs.change }}
    steps:
      - name: "📫 Checkout with history"
        uses: actions/checkout@v2
        with:
          fetch-depth: 0
      - id: graph_changes
        name: "🔎 Check for graph changes"
        uses: younited/detect-branch-changes-action@v0.1.3
        with:
          pathspec: "graph/"

  build_graph:
    name: "🧱 Graph"
    needs:
      - detect_changes
    runs-on: ubuntu-latest
    steps:
      - name: "🔬 Example test"
        run: echo OK

  test_graph_dumped_correctly:
    name: "🧪 Graph dumped correctly"
    needs:
      - build_graph
    runs-on: ubuntu-latest
    env:
      GEMS_CACHE_DIR: /tmp/bundle
    steps:
      - name: "🦘 Skipping?"
        if: needs.detect_changes.outputs.graph == 'false'
        run: echo Skipped
      - name: "📫 Checkout"
        if: needs.detect_changes.outputs.graph == 'true'
        uses: actions/checkout@v2
      - name: "🔬 Example test"
        if: needs.detect_changes.outputs.graph == 'true'
        run: echo OK

This file passes validation, but has a fairly big bug in it. The job test_graph_dumped_correctly uses needs.detect_changes but it is not defined in the the needs section of that job.
The bug is subtle, as the jobs will be executed in the expected order (due to the build_graph job in between). However the GitHub docs are clear that an explicit needs is required.

Job outputs are available to all downstream jobs that depend on this job.
https://docs.github.com/en/actions/using-jobs/defining-outputs-for-jobs#overview

It would be great if this check could be added as well.

[rhysd]

This was fixed in v1.6.17.