From d63f82c8da19a81bef8afd55601b1570404c3d23 Mon Sep 17 00:00:00 2001
From: Aaron Sikes <aaron@sikes.io>
Date: Wed, 10 May 2017 18:16:19 -0400
Subject: [PATCH] [BUGFIX beta] Preserve current history state

---
 .../lib/location/history_location.js          |  9 +++++++-
 .../tests/location/history_location_test.js   | 22 +++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/packages/ember-routing/lib/location/history_location.js b/packages/ember-routing/lib/location/history_location.js
index 1834aad836a..51c734f6827 100644
--- a/packages/ember-routing/lib/location/history_location.js
+++ b/packages/ember-routing/lib/location/history_location.js
@@ -64,7 +64,14 @@ export default EmberObject.extend({
       this.supportsHistory = true;
     }
 
-    this.replaceState(this.formatURL(this.getURL()));
+    let state = this.getState();
+    let path = this.formatURL(this.getURL());
+    if (state && state.path === path) { // preserve existing state
+      // used for webkit workaround, since there will be no initial popstate event
+      this._previousURL = this.getURL();
+    } else {
+      this.replaceState(path);
+    }
   },
 
   /**
diff --git a/packages/ember-routing/tests/location/history_location_test.js b/packages/ember-routing/tests/location/history_location_test.js
index 7e73d3304b7..c50d176276c 100644
--- a/packages/ember-routing/tests/location/history_location_test.js
+++ b/packages/ember-routing/tests/location/history_location_test.js
@@ -304,3 +304,25 @@ QUnit.test('HistoryLocation.getURL() drops duplicate slashes', function() {
 
   equal(location.getURL(), '/');
 });
+
+QUnit.test('Existing state is preserved on init', function() {
+  expect(1);
+
+  let existingState = {
+    path: '/route/path',
+    uuid: 'abcd'
+  };
+
+  FakeHistory.state = existingState;
+
+  HistoryTestLocation.reopen({
+    init() {
+      this._super(...arguments);
+      set(this, 'location', mockBrowserLocation('/route/path'));
+    }
+  });
+
+  createLocation();
+  location.initState();
+  deepEqual(location.getState(), existingState);
+});