Code coverage pre-QA push.

test/baseTest.ts

@@ -0,0 +1,55 @@
+import { test as base, expect, Page, TestInfo } from "@playwright/test";
+import * as crypto from "crypto";
+import * as fs from "fs";
+import * as path from "path";
+
+const NYC_OUTPUT_DIR = path.resolve(__dirname, "../.nyc_output");
+
+/**
+ * Extended Playwright test that automatically collects Istanbul code coverage
+ * from all frames after each test. Coverage is only collected when the
+ * COVERAGE environment variable is set to "true".
+ *
+ * Istanbul instrumentation must be enabled in the webpack build (see webpack.config.js).
+ * The instrumented code exposes `window.__coverage__` which this fixture collects.
+ */
+export const test = base.extend<{ coverageAutoCollect: void }>({
+  coverageAutoCollect: [
+    async ({ page }: { page: Page }, use: () => Promise<void>, testInfo: TestInfo) => {
+      // Run the test
+      await use();
+
+      // After the test, collect coverage if enabled
+      if (process.env.COVERAGE !== "true") {
+        return;
+      }
+
+      // Ensure the output directory exists
+      if (!fs.existsSync(NYC_OUTPUT_DIR)) {
+        fs.mkdirSync(NYC_OUTPUT_DIR, { recursive: true });
+      }
+
+      // Collect coverage from all frames (the app runs inside an iframe)
+      for (const frame of page.frames()) {
+        try {
+          const coverage = await frame.evaluate(() => {
+            // eslint-disable-next-line @typescript-eslint/no-explicit-any
+            return (window as any).__coverage__ || null;
+          });
+
+          if (coverage) {
+            const uniqueId = crypto.randomBytes(8).toString("hex");
+            const safeName = testInfo.title.replace(/[^a-zA-Z0-9]/g, "_").substring(0, 60);
+            const filename = `coverage-${safeName}-${uniqueId}.json`;
+            fs.writeFileSync(path.join(NYC_OUTPUT_DIR, filename), JSON.stringify(coverage));
+          }
+        } catch {
+          // Frame may have been detached or navigated away. That's fine, skip it.
+        }
+      }
+    },
+    { auto: true },
+  ],
+});
+
+export { expect };