gecko-dev/dom/indexedDB/test/browser_private_idb.js

async function idbCheckFunc() {
  let factory, console;
  try {
    // in a worker, this resolves directly.
    factory = indexedDB;
    console = self.console;
  } catch (ex) {
    // in a frame-script, we need to pierce "content"
    factory = content.indexedDB;
    console = content.console;
  }
  try {
    console.log("opening db");
    const req = factory.open("db", 1);
    const result = await new Promise((resolve, reject) => {
      req.onerror = () => {
        resolve("error");
      };
      // we expect the db to not exist and for created to resolve first
      req.onupgradeneeded = () => {
        resolve("created");
      };
      // ...so this will lose the race
      req.onsuccess = event => {
        resolve("already-exists");
      };
    });
    const db = req.result;
    console.log("db req completed:", result);
    if (result !== "error") {
      db.close();
      console.log("deleting database");
      await new Promise((resolve, reject) => {
        const delReq = factory.deleteDatabase("db");
        delReq.onerror = reject;
        delReq.onsuccess = resolve;
      });
      console.log("deleted database");
    }
    return result;
  } catch (ex) {
    console.error("received error:", ex);
    return "exception";
  }
}

async function workerDriverFunc() {
  const resultPromise = idbCheckFunc();
  /* eslint-env worker */
  // (SharedWorker)
  if (!("postMessage" in self)) {
    addEventListener("connect", function(evt) {
      const port = evt.ports[0];
      resultPromise.then(result => {
        console.log("worker test completed, postMessage-ing result:", result);
        port.postMessage({ idbResult: result });
      });
    });
  }
  const result = await resultPromise;
  // (DedicatedWorker)
  if ("postMessage" in self) {
    console.log("worker test completed, postMessage-ing result:", result);
    postMessage({ idbResult: result });
  }
}

const workerScript = `
${idbCheckFunc.toSource()}
(${workerDriverFunc.toSource()})();
`;
const workerScriptBlob = new Blob([workerScript]);

/**
 * This function is deployed via ContextTask.spawn and operates in a tab
 * frame script context.  Its job is to create the worker that will run the
 * idbCheckFunc and return the result to us.
 */
async function workerCheckDeployer({ srcBlob, workerType }) {
  const { console } = content;
  let worker, port;
  const url = content.URL.createObjectURL(srcBlob);
  if (workerType === "dedicated") {
    worker = new content.Worker(url);
    port = worker;
  } else if (workerType === "shared") {
    worker = new content.SharedWorker(url);
    port = worker.port;
    port.start();
  } else {
    throw new Error("bad worker type!");
  }

  const result = await new Promise((resolve, reject) => {
    port.addEventListener(
      "message",
      function(evt) {
        resolve(evt.data.idbResult);
      },
      { once: true }
    );
    worker.addEventListener("error", function(evt) {
      console.error("worker problem:", evt);
      reject(evt);
    });
  });
  console.log("worker completed test with result:", result);

  return result;
}

function checkTabWindowIDB(tab) {
  return SpecialPowers.spawn(tab.linkedBrowser, [], idbCheckFunc);
}

async function checkTabDedicatedWorkerIDB(tab) {
  return SpecialPowers.spawn(
    tab.linkedBrowser,
    [
      {
        srcBlob: workerScriptBlob,
        workerType: "dedicated",
      },
    ],
    workerCheckDeployer
  );
}

async function checkTabSharedWorkerIDB(tab) {
  return SpecialPowers.spawn(
    tab.linkedBrowser,
    [
      {
        srcBlob: workerScriptBlob,
        workerType: "shared",
      },
    ],
    workerCheckDeployer
  );
}

add_task(async function() {
  const pageUrl =
    "http://example.com/browser/dom/indexedDB/test/page_private_idb.html";

  let normalWin = await BrowserTestUtils.openNewBrowserWindow();
  let privateWin = await BrowserTestUtils.openNewBrowserWindow({
    private: true,
  });

  let normalTab = await BrowserTestUtils.openNewForegroundTab(
    normalWin.gBrowser,
    pageUrl
  );
  let privateTab = await BrowserTestUtils.openNewForegroundTab(
    privateWin.gBrowser,
    pageUrl
  );

  is(
    await checkTabWindowIDB(normalTab),
    "created",
    "IndexedDB works in a non-private-browsing page."
  );
  is(
    await checkTabWindowIDB(privateTab),
    "error",
    "IndexedDB does not work in a private-browsing page."
  );

  is(
    await checkTabDedicatedWorkerIDB(normalTab),
    "created",
    "IndexedDB works in a non-private-browsing Worker."
  );
  is(
    await checkTabDedicatedWorkerIDB(privateTab),
    "error",
    "IndexedDB does not work in a private-browsing Worker."
  );

  is(
    await checkTabSharedWorkerIDB(normalTab),
    "created",
    "IndexedDB works in a non-private-browsing SharedWorker."
  );
  is(
    await checkTabSharedWorkerIDB(privateTab),
    "error",
    "IndexedDB does not work in a private-browsing SharedWorker."
  );

  await BrowserTestUtils.closeWindow(normalWin);
  await BrowserTestUtils.closeWindow(privateWin);
});