chore: test commit lint change (#1863)

* chore: test commit lint change (1/n)
* chore: test spaces (2/n)
* chore: test github.event.distinct_size (3/n)
* chore: test the original command's meaning (4/n)
* chore: filter on just commit IDs for counting (5/n)
* chore: tidy up pull request template (6/n)
* chore: document where the filtering technique comes from (7/n)

.github/pull_request_template.md

@@ -1,4 +1,3 @@
-### Summary:
 
 ### Test Plan:
 
@@ -9,5 +8,5 @@
 - [ ] Wrote [automated tests](https://czi.atlassian.net/wiki/x/Hbl1H)
 - [ ] CI tests / new tests are not applicable
 - [ ] Manually tested my changes, but I want to keep the details secret
+- [ ] Created and used an [alpha publish](https://github.com/chanzuckerberg/edu-design-system/blob/main/docs/PUBLISHING.md#alpha-release)
 - [ ] Manually tested my changes, and here are the details:
-  - Create an [alpha publish](https://github.com/chanzuckerberg/edu-design-system/blob/main/docs/PUBLISHING.md#alpha-release) and try out in `edu-stack` or `traject` as a sanity check if changes affect build or deploy, or are breaking, such as token changes, widely used component updates, hooks changes, and major dependency upgrades.

.github/workflows/test.yml

@@ -122,9 +122,10 @@ jobs:
       - name: Validate commits commitlint
         # This workflow can also be triggered via "workflow_call".
         # Since it's a push event we have access to these properties https://docs.github.com/en/webhooks/webhook-events-and-payloads#push
+        # Filtering on just the (required) .id https://docs.github.com/en/actions/learn-github-actions/expressions#object-filters
         if: github.event_name == 'push'
         run: |
-          COMMIT_COUNT=$(echo '${{ toJSON(github.event.commits) }}' | jq length)
+          COMMIT_COUNT=$(echo '${{ toJSON(github.event.commits.*.id) }}' | jq length)
           echo "Number of commits in the push: $COMMIT_COUNT"
 
           yarn commitlint --from HEAD~$COMMIT_COUNT --to HEAD --verbose