Add an integration-test for merging a password-protected PDF

Looking at the coverage data the password-handling part of the merge functionality wasn't being tested; see e75a7cfd62/blob/src/core/worker.js (L652)

test/integration/reorganize_pages_spec.mjs

@@ -3399,6 +3399,67 @@ describe("Reorganize Pages View", () => {
       );
     });
 
+    it("should merge a password-protected PDF after the current page", async () => {
+      await Promise.all(
+        pages.map(async ([browserName, page]) => {
+          await waitForThumbnailVisible(page, 1);
+
+          // Navigate to page 2 so the merged PDF is inserted after it.
+          await page.evaluate(() => {
+            window.PDFViewerApplication.page = 2;
+          });
+          await page.waitForFunction(
+            () => window.PDFViewerApplication.page === 2
+          );
+          await waitAndClick(page, getThumbnailSelector(2));
+
+          const handleMerged = await createPromise(page, resolve => {
+            window.PDFViewerApplication.eventBus.on(
+              "thumbnailsloaded",
+              resolve,
+              { once: true }
+            );
+          });
+
+          const picker = await page.$("#viewsManagerAddFilePicker");
+          await picker.uploadFile(
+            path.join(__dirname, "../pdfs/issue6010_1.pdf")
+          );
+
+          // Test with an incorrect password first,
+          // to ensure that re-prompting works correctly.
+          for (const password of ["Incorrect password", "abc"]) {
+            await page.waitForSelector("#passwordDialog", { visible: true });
+            await page.type("#password", password);
+            await page.keyboard.press("Enter");
+          }
+
+          await awaitPromise(handleMerged);
+
+          // Original 3 pages + 1 merged page = 4 pages total.
+          await page.waitForFunction(
+            () => parseInt(document.getElementById("pageNumber").max, 10) === 4
+          );
+
+          // Focus must move to the first newly inserted page (page 3, since
+          // we merged after page 2).
+          await page.waitForFunction(
+            () => window.PDFViewerApplication.page === 3
+          );
+
+          // Pages 1–2 come from the original document, then the page of
+          // the merged PDF, then page 3 of the original shifted to the end.
+          await waitForHavingContents(page, [1, 2, "Issue 6010", 3]);
+
+          await waitForTextToBe(
+            page,
+            "#viewsManagerStatusActionLabel",
+            `${FSI}1${PDI} selected`
+          );
+        })
+      );
+    });
+
     it("should merge a corrupt PDF (with invalid pages /Count) after the current page", async () => {
       await Promise.all(
         pages.map(async ([browserName, page]) => {