Add review checking script

Simplify with workflow event

Remove condition for approval

Also run when unlabeled

Colourise output

.github/workflows/check-required-reviews.yml

@@ -2,15 +2,13 @@ name: Check required reviews
 
 on:
   pull_request:
-    types: [labeled]
+    types: [labeled, unlabeled]
   pull_request_review:
     types: [submitted]
 
 jobs:
   check-reviews:
-    # Only run if passing the basic GitHub review requirements.
-    # TODO: Removed for testing, so uncomment.
-    # if: github.event.review.state == 'APPROVED'
+    if: contains(github.event.pull_request.labels.*.name, 'full_review')
     runs-on: ubuntu-latest
     steps:
       - name: Set up Python
@@ -20,19 +18,41 @@ jobs:
 
       - name: Check reviews
         env:
-          PR_REF: github.ref
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         shell: python
         run: |
+          """Check there are enough approving reviews."""
+          import json
           import os
+          import re
+          import subprocess
           import sys
 
-          ref = os.getenv("PR_REF")
-          print(f"Ref: {ref}")
+          REQUIRED_REVIEWS = 3
 
-          # Get info with gh pr -R MetOffice/CSET view $PR_NUMBER --json
-          # labels,reviews If full_review label exists parse with program to see
-          # if enough reviews. Newer reviews by the same person should
-          # invalidate older reviews.
+          repo = "${{ github.repository }}"
+          pr_number = "${{ github.event.pull_request.number }}"
 
-          sys.exit(0)
+          # Get info on PR labels and reviews.
+          pr_info = json.loads(
+              subprocess.run(
+                  ("gh", "pr", "--json", "reviews", "--repo", repo, "view", pr_number),
+                  check=True,
+                  capture_output=True,
+                  timeout=60,
+                  text=True,
+              ).stdout
+          )
+
+          # Check for enough reviews. Newer reviews invalidate older ones.
+          approving_reviewers = set()
+          for review in sorted(pr_info["reviews"], key=lambda r: r["submittedAt"]):
+              if review["state"] == "APPROVED":
+                  approving_reviewers.add(review["author"]["login"])
+              elif review["state"] == "CHANGES_REQUESTED":
+                  approving_reviewers.discard(review["author"]["login"])
+
+          if len(approving_reviewers) < REQUIRED_REVIEWS:
+              print(f"\033[31m❌ Not enough reviews.\033[0m ({len(approving_reviewers)}/{REQUIRED_REVIEWS})")
+              sys.exit(1)
+          print(f"\033[32m✔ Sufficient reviews.\033[0m ({len(approving_reviewers)}/{REQUIRED_REVIEWS})")