Fail PR if code coverage drops vs master baseline

andimarek · claude · andimarek · commit 997ce34d35c3 · 2026-03-05T20:05:51.000+10:00
Add a coverage gate in the test-summary job that checks line, branch,
and method coverage against the master baseline. The PR comment is
posted first so developers always see the report, then core.setFailed()
is called if any metric decreased.

Co-Authored-By: Claude Opus 4.6 &lt;noreply@anthropic.com&gt;
diff --git a/.github/workflows/pull_request.yml b/.github/workflows/pull_request.yml
@@ -363,6 +363,27 @@ jobs:
                 body,
               });
             }
+
+            // --- Coverage gate: fail if any metric drops ---
+            if (covLine || covBranch || covMethod) {
+              const drops = [];
+              for (const { name, curr, baseKey } of [
+                { name: 'Line', curr: covLine, baseKey: 'line' },
+                { name: 'Branch', curr: covBranch, baseKey: 'branch' },
+                { name: 'Method', curr: covMethod, baseKey: 'method' },
+              ]) {
+                if (!curr) continue;
+                const b = baseCov[baseKey] || zeroCov;
+                const currPct = pct(curr.covered, curr.missed);
+                const basePct = pct(b.covered, b.missed);
+                if (currPct < basePct - 0.05) {
+                  drops.push(`${name}: ${currPct.toFixed(1)}% (was ${basePct.toFixed(1)}%, delta ${(currPct - basePct).toFixed(1)}%)`);
+                }
+              }
+              if (drops.length > 0) {
+                core.setFailed(`Coverage decreased:\n${drops.join('\n')}`);
+              }
+            }
   javadoc:
     runs-on: ubuntu-latest
     steps:
