1 files changed, 57 insertions, 0 deletions
diff --git a/docshell/test/navigation/browser_test_simultaneous_normal_and_history_loads.js b/docshell/test/navigation/browser_test_simultaneous_normal_and_history_loads.js
new file mode 100644
index 0000000000..a400d15466
--- /dev/null
+++ b/docshell/test/navigation/browser_test_simultaneous_normal_and_history_loads.js
@@ -0,0 +1,57 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+add_task(async function test_normal_and_history_loads() {
+  // This test is for the case when session history lives in the parent process.
+  // BFCache is disabled to get more asynchronousness.
+  await SpecialPowers.pushPrefEnv({
+    set: [["fission.bfcacheInParent", false]],
+  });
+
+  let testPage =
+    getRootDirectory(gTestPath).replace(
+      "chrome://mochitests/content",
+      // eslint-disable-next-line @microsoft/sdl/no-insecure-url
+      "http://example.com"
+    ) + "blank.html";
+  await BrowserTestUtils.withNewTab(
+    { gBrowser, url: testPage },
+    async function (browser) {
+      for (let i = 0; i < 2; ++i) {
+        BrowserTestUtils.loadURIString(browser, testPage + "?" + i);
+        await BrowserTestUtils.browserLoaded(browser);
+      }
+
+      let sh = browser.browsingContext.sessionHistory;
+      is(sh.count, 3, "Should have 3 entries in the session history.");
+      is(sh.index, 2, "index should be 2");
+      is(sh.requestedIndex, -1, "requestedIndex should be -1");
+
+      // The following part is racy by definition. It is testing that
+      // eventually requestedIndex should become -1 again.
+      browser.browsingContext.goToIndex(1);
+      let historyLoad = BrowserTestUtils.browserLoaded(browser);
+      /* eslint-disable mozilla/no-arbitrary-setTimeout */
+      await new Promise(r => {
+        setTimeout(r, 10);
+      });
+      browser.browsingContext.loadURI(
+        Services.io.newURI(testPage + "?newload"),
+        {
+          triggeringPrincipal: browser.nodePrincipal,
+        }
+      );
+      let newLoad = BrowserTestUtils.browserLoaded(browser);
+      // Note, the loads are racy.
+      await historyLoad;
+      await newLoad;
+      is(sh.requestedIndex, -1, "requestedIndex should be -1");
+
+      browser.browsingContext.goBack();
+      await BrowserTestUtils.browserLoaded(browser);
+      is(sh.requestedIndex, -1, "requestedIndex should be -1");
+    }
+  );
+});