gecko-dev/docshell/test/browser/browser_multiple_pushState.js

add_task(async function test_multiple_pushState() {
  await BrowserTestUtils.withNewTab({
    gBrowser,
    url: "http://example.org/browser/docshell/test/browser/file_multiple_pushState.html",
  }, async function(browser) {
    const kExpected = "http://example.org/bar/ABC/DEF?key=baz";

    let contentLocation = await ContentTask.spawn(browser, null, async function() {
      return content.document.location.href;
    });

    is(contentLocation, kExpected);
    is(browser.documentURI.spec, kExpected);
  });
});