check PR description for a BUG= line (#187)

* check PR description for a BUG= line

* Changed file name and added some more documentation.

* move the if to be on the steo instead of at the job.

This is to allow for the job to succeed (instead of being skipped) when
the BUG= text is found. And as a result we can have it be a required
status check.
Co-authored-by: NAdvait Jain <advaitjain@users.noreply.github.com>
Co-authored-by: NAdvait Jain <advaitjain@google.com>

.github/workflows/check_pr_has_bug.yml

+name: Check PR has Bug
+on:
+  pull_request:
+    types: [labeled]
+
+jobs:
+  find-bug-tag:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check for BUG=
+        if: ${{ !contains(github.event.pull_request.body, 'BUG=') }}
+        run: |
+          echo "PR description requires a BUG= line with issue number."
+          echo "See https://testing.googleblog.com/2017/09/code-health-providing-context-with.html for additional context"
+          exit 1

CONTRIBUTING.md

@@ -101,9 +101,8 @@ We strongly recommend that contributors:
 
         *   While github offers flexibility in linking
             [commits and issues](https://github.blog/2011-04-09-issues-2-0-the-next-generation/#commits-issues),
-            we require that the PR description have a separate line with either
-            `Fixes #nn` (if the PR fixes the issue) or `Issue #nn` if the PR
-            addresses some aspect of an issue without fixing it.
+            we require that the PR description have a separate line with
+            `BUG=#nn`.
 
         *   We will be adding internal checks that automate this requirement by
             matching the PR description to the regexp: `(Fixes|Issue) #`