coverage generation for playwright tests

only generates the istanbul coverage for the initial page object in
the main context fixture.
Still missing is coverage for the auth setup, coverage for any popup
pages (like the sidebar pages) and the background worker.

end-to-end-tests/fixtures/extensionBase.ts

@@ -29,6 +29,8 @@ import {
 } from "./utils";
 import { ModsPage } from "../pageObjects/extensionConsole/modsPage";
 import { test as envSetup } from "./envSetup";
+import v8toIstanbul from "v8-to-istanbul";
+import { v4 } from "uuid";
 
 // This environment variable is used to attach the browser sidepanel window that opens automatically to Playwright.
 // See https://github.com/microsoft/playwright/issues/26693
@@ -38,6 +40,16 @@ process.env.PW_CHROMIUM_ATTACH_TO_OTHER = "1";
 // See https://playwright.dev/docs/service-workers-experimental
 process.env.PW_EXPERIMENTAL_SERVICE_WORKER_NETWORK_EVENTS = "1";
 
+const coverageDirectory = path.join(__dirname, "../.output/coverage");
+
+const collectCoverage = async (coverageJSON: string) => {
+  if (coverageJSON)
+    await fs.writeFile(
+      `${coverageDirectory}/playwright_coverage_${v4()}.json`,
+      coverageJSON,
+    );
+};
+
 export const test = mergeTests(
   envSetup,
   base.extend<
@@ -83,6 +95,10 @@ export const test = mergeTests(
         recursive: true,
       });
 
+      await fs.mkdir(coverageDirectory, {
+        recursive: true,
+      });
+
       const context = await launchPersistentContextWithExtension(
         chromiumChannel,
         temporaryProfileDirectory,
@@ -94,12 +110,20 @@ export const test = mergeTests(
     async page({ context, extensionId }, use) {
       // Re-use the initial context page if it exists
       const page = context.pages()[0] || (await context.newPage());
+      await page.coverage.startJSCoverage();
 
       // Start off test from the extension console, and ensure it is done loading
       const modsPage = new ModsPage(page, extensionId);
       await modsPage.goto();
 
       await use(page);
+      const coverage = await page.coverage.stopJSCoverage();
+      for (const entry of coverage) {
+        const converter = v8toIstanbul("", 0, { source: entry.source });
+        await converter.load();
+        converter.applyCoverage(entry.functions);
+        await collectCoverage(JSON.stringify(converter.toIstanbul()));
+      }
       // The page is closed by the context fixture `.close` cleanup step
     },
     async extensionId({ context }, use) {

package.json

@@ -290,6 +290,7 @@
     "type-fest": "^4.18.0",
     "typescript": "^5.4.5",
     "typescript-plugin-css-modules": "^5.1.0",
+    "v8-to-istanbul": "^9.2.0",
     "webpack": "^5.91.0",
     "webpack-build-notifier": "^2.3.0",
     "webpack-bundle-analyzer": "^4.10.2",