Add support for query params to the TrailingHistory location

app/locations/trailing-history.js

@@ -4,11 +4,14 @@ import HistoryLocation from '@ember/routing/history-location';
 export default HistoryLocation.extend({
   formatURL() {
     let url = this._super(...arguments);
+    return formatURL(url);
+  },
+});
 
-    if (url.includes('#')) {
-      return url.replace(/([^/])#(.*)/, '$1/#$2');
-    } else {
-      return url.replace(/\/?$/, '/');
-    }
+export function formatURL(url) {
+  let modifiedURL = new URL(url, 'http://example.com');
+  if (!modifiedURL.pathname.endsWith('/')) {
+    modifiedURL.pathname += '/';
   }
-});
+  return `${modifiedURL.pathname}${modifiedURL.search}${modifiedURL.hash}`;
+}

tests/unit/locations/trailing-history-test.js

@@ -0,0 +1,26 @@
+import { module, test } from 'qunit';
+import { setupTest } from 'ember-qunit';
+import { formatURL } from 'dummy/locations/trailing-history';
+
+module('Unit | Locations | trailing history', function (hooks) {
+  setupTest(hooks);
+
+  test('supports query params', function (assert) {
+    assert.deepEqual(formatURL('/foo?bar=baz'), '/foo/?bar=baz');
+  });
+
+  test('supports anchors', function (assert) {
+    assert.deepEqual(formatURL('/foo#placeholder'), '/foo/#placeholder');
+  });
+
+  test('does not add double slashes', function (assert) {
+    assert.deepEqual(formatURL('/foo/'), '/foo/');
+  });
+
+  test('supports query params and anchors', function (assert) {
+    assert.deepEqual(
+      formatURL('/foo?bar=baz#placeholder'),
+      '/foo/?bar=baz#placeholder',
+    );
+  });
+});