From 003054460bac73568743ca7337196d854eeaf5a9 Mon Sep 17 00:00:00 2001
From: gnezim <gnezim@gmail.com>
Date: Wed, 15 Apr 2026 16:33:01 +0300
Subject: [PATCH] Add coverage delta check script

---
 package.json                        |  3 +-
 scripts/ci/check-coverage-delta.mjs | 58 +++++++++++++++++++++++++++++
 2 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 scripts/ci/check-coverage-delta.mjs

diff --git a/package.json b/package.json
index 9666130a..ac5d5a69 100644
--- a/package.json
+++ b/package.json
@@ -19,7 +19,8 @@
     "test:coverage": "vitest run --coverage",
     "lint": "eslint \"src/**/*.{ts,tsx}\" --max-warnings 0",
     "typecheck": "tsc --noEmit",
-    "bundle-size": "node scripts/ci/bundle-size-gate.mjs"
+    "bundle-size": "node scripts/ci/bundle-size-gate.mjs",
+    "check-coverage": "node scripts/ci/check-coverage-delta.mjs"
   },
   "dependencies": {
     "@microsoft/signalr": "^10.0.0",
diff --git a/scripts/ci/check-coverage-delta.mjs b/scripts/ci/check-coverage-delta.mjs
new file mode 100644
index 00000000..e0d904ae
--- /dev/null
+++ b/scripts/ci/check-coverage-delta.mjs
@@ -0,0 +1,58 @@
+/**
+ * Coverage gate for CI.
+ *
+ * Reads coverage-summary.json (Vitest --coverage output) and fails
+ * if overall line coverage drops below the configured threshold.
+ *
+ * Usage:
+ *   pnpm test:coverage
+ *   node scripts/ci/check-coverage-delta.mjs
+ *
+ * Environment variable overrides:
+ *   COVERAGE_THRESHOLD  – minimum line coverage % (default: 65)
+ *   COVERAGE_FILE       – path to coverage-summary.json
+ */
+
+import { readFileSync } from "node:fs";
+
+const THRESHOLD = Number(process.env.COVERAGE_THRESHOLD ?? 65);
+const COVERAGE_FILE =
+  process.env.COVERAGE_FILE ?? "coverage/coverage-summary.json";
+
+let summary;
+try {
+  summary = JSON.parse(readFileSync(COVERAGE_FILE, "utf8"));
+} catch (err) {
+  console.error(`Could not read ${COVERAGE_FILE}: ${err.message}`);
+  console.error("Run `pnpm test:coverage` first.");
+  process.exit(1);
+}
+
+const total = summary.total;
+if (!total) {
+  console.error(`No "total" key in ${COVERAGE_FILE}`);
+  process.exit(1);
+}
+
+const linePct = total.lines?.pct ?? 0;
+const branchPct = total.branches?.pct ?? 0;
+const fnPct = total.functions?.pct ?? 0;
+const stmtPct = total.statements?.pct ?? 0;
+
+console.log("\n--- Coverage Report ---\n");
+console.log(`  Lines:      ${linePct.toFixed(2)}%`);
+console.log(`  Branches:   ${branchPct.toFixed(2)}%`);
+console.log(`  Functions:  ${fnPct.toFixed(2)}%`);
+console.log(`  Statements: ${stmtPct.toFixed(2)}%`);
+console.log(`\n  Threshold:  ${THRESHOLD}% (lines)\n`);
+
+if (linePct < THRESHOLD) {
+  console.error(
+    `FAILED: Line coverage ${linePct.toFixed(2)}% is below the ${THRESHOLD}% threshold`
+  );
+  process.exit(1);
+} else {
+  console.log(
+    `PASSED: Line coverage ${linePct.toFixed(2)}% meets the ${THRESHOLD}% threshold`
+  );
+}