fork from https://github.com/mozilla/pdf.js.git

test/coverage_utils.js

@@ -0,0 +1,58 @@
+/* Copyright 2026 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Istanbul coverage objects use s (statements), b (branches), and f (functions)
+// as shorthand keys for the hit-count maps.
+function mergeCoverageIntoGlobal(coverage) {
+  if (!coverage || Object.keys(coverage).length === 0) {
+    return;
+  }
+  globalThis.__coverage__ ??= {};
+  for (const [key, fileCoverage] of Object.entries(coverage)) {
+    const existing = globalThis.__coverage__[key];
+    if (!existing) {
+      globalThis.__coverage__[key] = fileCoverage;
+      continue;
+    }
+    for (const id of Object.keys(fileCoverage.s)) {
+      existing.s[id] = (existing.s[id] ?? 0) + fileCoverage.s[id];
+    }
+    for (const id of Object.keys(fileCoverage.b)) {
+      existing.b[id] = fileCoverage.b[id].map(
+        (c, i) => (existing.b[id]?.[i] ?? 0) + c
+      );
+    }
+    for (const id of Object.keys(fileCoverage.f)) {
+      existing.f[id] = (existing.f[id] ?? 0) + fileCoverage.f[id];
+    }
+  }
+}
+
+async function fetchAndMergeWorkerCoverage(pdfWorker) {
+  if (!pdfWorker) {
+    return;
+  }
+  try {
+    const coverage = await pdfWorker.messageHandler.sendWithPromise(
+      "GetWorkerCoverage",
+      null
+    );
+    mergeCoverageIntoGlobal(coverage);
+  } catch (e) {
+    console.warn(`Failed to collect worker coverage: ${e}`);
+  }
+}
+
+export { fetchAndMergeWorkerCoverage, mergeCoverageIntoGlobal };