Fix intermittent failure in the stamp editor's undo-related integration tests

The clipboard, used via the `copyImage` helper function, is a shared
resource, so access to it cannot happen concurrently because it could
result in tests overwriting each other's contents. Most tests using
the clipboard are therefore run sequentially, but only the stamp
editor's undo-related tests weren't, so this commit fixes the issue
by running those tests sequentially too.

Author: timvandermeij

test/integration/stamp_editor_spec.mjs

@@ -631,6 +631,7 @@ describe("Stamp Editor", () => {
     });
 
     it("must check that the alt-text button is here when pasting in the second tab", async () => {
+      // Run sequentially to avoid clipboard issues.
       for (let i = 0; i < pages1.length; i++) {
         const [, page1] = pages1[i];
         await page1.bringToFront();
@@ -1592,86 +1593,80 @@ describe("Stamp Editor", () => {
     });
 
     it("must check that deleting an image can be undone using the undo button", async () => {
-      await Promise.all(
-        pages.map(async ([browserName, page]) => {
-          await switchToStamp(page);
+      // Run sequentially to avoid clipboard issues.
+      for (const [, page] of pages) {
+        await switchToStamp(page);
 
-          const editorSelector = getEditorSelector(0);
-          await copyImage(page, "../images/firefox_logo.png", editorSelector);
-          await page.waitForSelector(editorSelector);
-          await waitForSerialized(page, 1);
+        const editorSelector = getEditorSelector(0);
+        await copyImage(page, "../images/firefox_logo.png", editorSelector);
+        await page.waitForSelector(editorSelector);
+        await waitForSerialized(page, 1);
 
-          await page.waitForSelector(`${editorSelector} button.delete`);
-          await page.click(`${editorSelector} button.delete`);
-          await waitForSerialized(page, 0);
-          await page.waitForSelector("#editorUndoBar", { visible: true });
+        await page.waitForSelector(`${editorSelector} button.delete`);
+        await page.click(`${editorSelector} button.delete`);
+        await waitForSerialized(page, 0);
+        await page.waitForSelector("#editorUndoBar", { visible: true });
 
-          await page.waitForSelector("#editorUndoBarUndoButton", {
-            visible: true,
-          });
-          await page.click("#editorUndoBarUndoButton");
-          await waitForSerialized(page, 1);
-          await page.waitForSelector(editorSelector);
-          await page.waitForSelector(`${editorSelector} canvas`);
-        })
-      );
+        await page.waitForSelector("#editorUndoBarUndoButton", {
+          visible: true,
+        });
+        await page.click("#editorUndoBarUndoButton");
+        await waitForSerialized(page, 1);
+        await page.waitForSelector(editorSelector);
+        await page.waitForSelector(`${editorSelector} canvas`);
+      }
     });
 
     it("must check that the undo deletion popup displays the correct message", async () => {
-      await Promise.all(
-        pages.map(async ([browserName, page]) => {
-          await switchToStamp(page);
+      // Run sequentially to avoid clipboard issues.
+      for (const [, page] of pages) {
+        await switchToStamp(page);
 
-          const editorSelector = getEditorSelector(0);
-          await copyImage(page, "../images/firefox_logo.png", editorSelector);
-          await page.waitForSelector(editorSelector);
-          await waitForSerialized(page, 1);
+        const editorSelector = getEditorSelector(0);
+        await copyImage(page, "../images/firefox_logo.png", editorSelector);
+        await page.waitForSelector(editorSelector);
+        await waitForSerialized(page, 1);
 
-          await page.waitForSelector(`${editorSelector} button.delete`);
-          await page.click(`${editorSelector} button.delete`);
-          await waitForSerialized(page, 0);
+        await page.waitForSelector(`${editorSelector} button.delete`);
+        await page.click(`${editorSelector} button.delete`);
+        await waitForSerialized(page, 0);
 
-          await page.waitForFunction(() => {
-            const messageElement = document.querySelector(
-              "#editorUndoBarMessage"
-            );
-            return messageElement && messageElement.textContent.trim() !== "";
-          });
-          const message = await page.waitForSelector("#editorUndoBarMessage");
-          const messageText = await page.evaluate(
-            el => el.textContent,
-            message
+        await page.waitForFunction(() => {
+          const messageElement = document.querySelector(
+            "#editorUndoBarMessage"
           );
-          expect(messageText).toContain("Image removed");
-        })
-      );
+          return messageElement && messageElement.textContent.trim() !== "";
+        });
+        const message = await page.waitForSelector("#editorUndoBarMessage");
+        const messageText = await page.evaluate(el => el.textContent, message);
+        expect(messageText).toContain("Image removed");
+      }
     });
 
     it("must check that the popup disappears when a new image is inserted", async () => {
-      await Promise.all(
-        pages.map(async ([browserName, page]) => {
-          await switchToStamp(page);
+      // Run sequentially to avoid clipboard issues.
+      for (const [, page] of pages) {
+        await switchToStamp(page);
 
-          const editorSelector = getEditorSelector(0);
-          await copyImage(page, "../images/firefox_logo.png", editorSelector);
-          await page.waitForSelector(editorSelector);
-          await waitForSerialized(page, 1);
+        const editorSelector = getEditorSelector(0);
+        await copyImage(page, "../images/firefox_logo.png", editorSelector);
+        await page.waitForSelector(editorSelector);
+        await waitForSerialized(page, 1);
 
-          await page.waitForSelector(`${editorSelector} button.delete`);
-          await page.click(`${editorSelector} button.delete`);
-          await waitForSerialized(page, 0);
+        await page.waitForSelector(`${editorSelector} button.delete`);
+        await page.click(`${editorSelector} button.delete`);
+        await waitForSerialized(page, 0);
 
-          await page.waitForSelector("#editorUndoBar", { visible: true });
-          await page.click("#editorStampAddImage");
-          const newInput = await page.$("#stampEditorFileInput");
-          await newInput.uploadFile(
-            `${path.join(__dirname, "../images/firefox_logo.png")}`
-          );
-          await waitForImage(page, getEditorSelector(1));
-          await waitForSerialized(page, 1);
-          await page.waitForSelector("#editorUndoBar", { hidden: true });
-        })
-      );
+        await page.waitForSelector("#editorUndoBar", { visible: true });
+        await page.click("#editorStampAddImage");
+        const newInput = await page.$("#stampEditorFileInput");
+        await newInput.uploadFile(
+          `${path.join(__dirname, "../images/firefox_logo.png")}`
+        );
+        await waitForImage(page, getEditorSelector(1));
+        await waitForSerialized(page, 1);
+        await page.waitForSelector("#editorUndoBar", { hidden: true });
+      }
     });
   });