webextension-polyfill/test/fixtures/runtime-messaging-extension/content.js

test("sendMessage with returned Promise reply", async (t) => {
  const reply = await browser.runtime.sendMessage("test - sendMessage with returned Promise reply");
  t.equal(reply, "bg page reply 1");
});

test("sendMessage with returned value reply", async (t) => {
  const reply = await browser.runtime.sendMessage("test - sendMessage with returned value reply");
  t.equal(reply, "second listener reply");
});

test("sendMessage with synchronous sendResponse", async (t) => {
  const reply = await browser.runtime.sendMessage("test - sendMessage with synchronous sendResponse");
  t.equal(reply, "bg page reply 3");
});

test("sendMessage with asynchronous sendResponse", async (t) => {
  const reply = await browser.runtime.sendMessage("test - sendMessage with asynchronous sendResponse");
  t.equal(reply, "bg page reply 4");
});

test("second listener if the first does not reply", async (t) => {
  const reply = await browser.runtime.sendMessage("test - second listener if the first does not reply");
  t.equal(reply, "second listener reply");
});

test("sendMessage with returned rejected Promise with Error value", async (t) => {
  try {
    const reply = await browser.runtime.sendMessage(
      "test - sendMessage with returned rejected Promise with Error value");
    t.fail(`Unexpected successfully reply while expecting a rejected promise`);
    t.equal(reply, undefined, "Unexpected successfully reply");
  } catch (err) {
    t.ok(err instanceof Error, "Got an error object as expected");
    t.equal(err.message, "rejected-error-value", "Got an error rejection with the expected message");
  }
});

test("sendMessage with returned rejected Promise with non-Error value", async (t) => {
  try {
    const reply = await browser.runtime.sendMessage(
      "test - sendMessage with returned rejected Promise with non-Error value");
    t.fail(`Unexpected successfully reply while expecting a rejected promise`);
    t.equal(reply, undefined, "Unexpected successfully reply");
  } catch (err) {
    // Unfortunately Firefox currently rejects an error with an "undefined"
    // message in Firefox 60 and "An unexpected error occurred" in Firefox 59,
    // in the meantime we just check that the object rejected is an instance
    // of Error.
    t.ok(err instanceof Error, "Got an error object as expected");
  }
});

test("sendMessage with returned rejected Promise with non-Error value with message property", async (t) => {
  try {
    const reply = await browser.runtime.sendMessage(
      "test - sendMessage with returned rejected Promise with non-Error value with message property");
    t.fail(`Unexpected successfully reply while expecting a rejected promise`);
    t.equal(reply, undefined, "Unexpected successfully reply");
  } catch (err) {
    // Firefox currently converts any rejection with a message property into an error instance
    // with the value of that message property as the error message.
    t.ok(err instanceof Error, "Got an error object as expected");
    t.equal(err.message, "rejected-non-error-message", "Got an error rejection with the expected message");
  }
});

test("sendMessage with listener callback throws", async (t) => {
  try {
    const reply = await browser.runtime.sendMessage(
      "test - sendMessage with listener callback throws");
    t.fail(`Unexpected successfully reply while expecting a rejected promise`);
    t.equal(reply, undefined, "Unexpected successfully reply");
  } catch (err) {
    t.ok(err instanceof Error, "Got an error object as expected");
    t.equal(err.message, "listener throws", "Got an error with the expected message");
  }
});