ci: split PR and release certification gates (#161)

scripts/check-changed-line-coverage.mjs

@@ -0,0 +1,64 @@
+#!/usr/bin/env node
+import { readFileSync } from 'node:fs';
+import { execFileSync } from 'node:child_process';
+
+export function changedLines(diff) {
+  const files = new Map();
+  let current;
+  for (const line of String(diff).split('\n')) {
+    if (line.startsWith('+++ b/')) {
+      current = line.slice(6);
+      if (!files.has(current)) files.set(current, new Set());
+      continue;
+    }
+    const match = line.match(/^@@ -\d+(?:,\d+)? \+(\d+)(?:,(\d+))? @@/);
+    if (!match || !current) continue;
+    const start = Number(match[1]);
+    const count = match[2] === undefined ? 1 : Number(match[2]);
+    for (let n = start; n < start + count; n += 1) files.get(current).add(n);
+  }
+  return files;
+}
+
+export function assessChangedCoverage(coverage, changes) {
+  let coverable = 0;
+  let covered = 0;
+  const uncovered = [];
+  for (const [file, lines] of changes) {
+    if (!file.startsWith('src/') || file.endsWith('.test.ts') || file.includes('/__tests__/')) continue;
+    const entry = Object.values(coverage).find((item) => String(item.path || '').replaceAll('\\', '/').endsWith(`/${file}`));
+    if (!entry) continue;
+    for (const line of lines) {
+      const statementIds = Object.entries(entry.statementMap || {})
+        .filter(([, span]) => line >= span.start.line && line <= span.end.line)
+        .map(([id]) => id);
+      if (!statementIds.length) continue;
+      coverable += 1;
+      if (statementIds.some((id) => Number(entry.s?.[id] || 0) > 0)) covered += 1;
+      else uncovered.push(`${file}:${line}`);
+    }
+  }
+  return { coverable, covered, percent: coverable ? (covered / coverable) * 100 : 100, uncovered };
+}
+
+function selfTest() {
+  const changes = changedLines('+++ b/src/a.ts\n@@ -1 +1,3 @@\n+x\n+y\n+z');
+  const coverage = { '/repo/src/a.ts': { path: '/repo/src/a.ts', statementMap: { 0: { start: { line: 1 }, end: { line: 1 } }, 1: { start: { line: 2 }, end: { line: 3 } } }, s: { 0: 1, 1: 0 } } };
+  const result = assessChangedCoverage(coverage, changes);
+  if (result.coverable !== 3 || result.covered !== 1 || Math.round(result.percent) !== 33) throw new Error('changed-line coverage self-test failed');
+  console.log('changed-line coverage self-test passed');
+}
+
+if (process.argv.includes('--self-test')) {
+  selfTest();
+} else {
+  const base = process.argv[2] || process.env.COVERAGE_BASE;
+  const minimum = Number(process.argv[3] || process.env.PR_CHANGED_LINE_COVERAGE || 50);
+  if (!base) throw new Error('base revision required as argv[2] or COVERAGE_BASE');
+  const diff = execFileSync('git', ['diff', '--unified=0', '--no-ext-diff', `${base}...HEAD`, '--', 'src'], { encoding: 'utf8' });
+  const coverage = JSON.parse(readFileSync('coverage-pr/coverage-final.json', 'utf8'));
+  const result = assessChangedCoverage(coverage, changedLines(diff));
+  console.log(`Changed executable lines: ${result.covered}/${result.coverable} (${result.percent.toFixed(1)}%; required ${minimum}%)`);
+  if (result.uncovered.length) console.log(`Uncovered changed lines:\n${result.uncovered.slice(0, 100).join('\n')}`);
+  if (result.percent < minimum) process.exitCode = 1;
+}