diff --git a/app/assets/javascripts/discourse/app/lib/ajax.js b/app/assets/javascripts/discourse/app/lib/ajax.js
index 2bdeb0459ea..45059a60750 100644
--- a/app/assets/javascripts/discourse/app/lib/ajax.js
+++ b/app/assets/javascripts/discourse/app/lib/ajax.js
@@ -119,9 +119,14 @@ export function ajax() {
 
     args.error = (xhr, textStatus, errorThrown) => {
       // 0 represents the `UNSENT` state
-      if (xhr.readyState === 0 && !isTesting()) {
+      if (xhr.readyState === 0) {
+        // Make sure we log pretender errors in test mode
+        if (isTesting()) {
+          throw errorThrown;
+        }
         return;
       }
+
       handleLogoff(xhr);
 
       // note: for bad CSRF we don't loop an extra request right away.
diff --git a/test/javascripts/acceptance/composer-test.js b/test/javascripts/acceptance/composer-test.js
index 235236a2d2a..de47599dad0 100644
--- a/test/javascripts/acceptance/composer-test.js
+++ b/test/javascripts/acceptance/composer-test.js
@@ -859,10 +859,6 @@ QUnit.test("can reply to a private message", async assert => {
     return [200, { "Content-Type": "application/json" }, {}];
   });
 
-  // a bit messy but we need a fake here cause we issue a route transition
-  // to the new post
-  server.get("/t/34/4.json", () => server.get("/t/34.json"));
-
   await visit("/t/34");
   await click(".topic-post:eq(0) button.reply");
   await fillIn(".d-editor-input", "this is the *content* of the reply");
diff --git a/test/javascripts/helpers/create-pretender.js b/test/javascripts/helpers/create-pretender.js
index 371e6517752..1ed9e4c4b05 100644
--- a/test/javascripts/helpers/create-pretender.js
+++ b/test/javascripts/helpers/create-pretender.js
@@ -2,20 +2,22 @@ import User from "discourse/models/user";
 
 export function parsePostData(query) {
   const result = {};
-  query.split("&").forEach(function(part) {
-    const item = part.split("=");
-    const firstSeg = decodeURIComponent(item[0]);
-    const m = /^([^\[]+)\[(.+)\]/.exec(firstSeg);
+  if (query) {
+    query.split("&").forEach(function(part) {
+      const item = part.split("=");
+      const firstSeg = decodeURIComponent(item[0]);
+      const m = /^([^\[]+)\[(.+)\]/.exec(firstSeg);
 
-    const val = decodeURIComponent(item[1]).replace(/\+/g, " ");
-    if (m) {
-      let key = m[1];
-      result[key] = result[key] || {};
-      result[key][m[2].replace("][", ".")] = val;
-    } else {
-      result[firstSeg] = val;
-    }
-  });
+      const val = decodeURIComponent(item[1]).replace(/\+/g, " ");
+      if (m) {
+        let key = m[1];
+        result[key] = result[key] || {};
+        result[key][m[2].replace("][", ".")] = val;
+      } else {
+        result[firstSeg] = val;
+      }
+    });
+  }
   return result;
 }
 
@@ -245,6 +247,7 @@ export function applyDefaultHandlers(pretender) {
 
   pretender.get("/t/280.json", () => response(fixturesByUrl["/t/280/1.json"]));
   pretender.get("/t/34.json", () => response(fixturesByUrl["/t/34/1.json"]));
+  pretender.get("/t/34/4.json", () => response(fixturesByUrl["/t/34/1.json"]));
   pretender.get("/t/280/:post_number.json", () =>
     response(fixturesByUrl["/t/280/1.json"])
   );
@@ -255,7 +258,9 @@ export function applyDefaultHandlers(pretender) {
   pretender.get("/t/12.json", () => response(fixturesByUrl["/t/12/1.json"]));
   pretender.put("/t/1234/re-pin", success);
 
-  pretender.get("/t/2480.json", () => response(fixturesByUrl["/t/2480/1.json"]));
+  pretender.get("/t/2480.json", () =>
+    response(fixturesByUrl["/t/2480/1.json"])
+  );
 
   pretender.get("/t/id_for/:slug", () => {
     return response({
diff --git a/test/javascripts/models/user-badge-test.js b/test/javascripts/models/user-badge-test.js
index 80d2432453b..870a8ad8fbe 100644
--- a/test/javascripts/models/user-badge-test.js
+++ b/test/javascripts/models/user-badge-test.js
@@ -4,7 +4,9 @@ import badgeFixtures from "fixtures/user-badges";
 QUnit.module("model:user-badge");
 
 QUnit.test("createFromJson single", assert => {
-  const userBadge = UserBadge.createFromJson(badgeFixtures["/user_badges"]);
+  const userBadge = UserBadge.createFromJson(
+    JSON.parse(JSON.stringify(badgeFixtures["/user_badges"]))
+  );
   assert.ok(!Array.isArray(userBadge), "does not return an array");
   assert.equal(
     userBadge.get("badge.name"),
@@ -25,7 +27,7 @@ QUnit.test("createFromJson single", assert => {
 
 QUnit.test("createFromJson array", assert => {
   const userBadges = UserBadge.createFromJson(
-    badgeFixtures["/user-badges/:username"]
+    JSON.parse(JSON.stringify(badgeFixtures["/user-badges/:username"]))
   );
   assert.ok(Array.isArray(userBadges), "returns an array");
   assert.equal(