From b0431d6884d335208161be1e562d3682da168d9d Mon Sep 17 00:00:00 2001
From: christopherthielen <github@sandgnat.com>
Date: Sat, 31 Jan 2015 16:45:43 -0600
Subject: [PATCH] fix(previous): Previous state no longer tracks abstract
 from-states (e.g., root)

 Closes #123
---
 src/previous.js      | 10 ++++++++--
 test/previousSpec.js | 16 +++++++++++++---
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/src/previous.js b/src/previous.js
index ee368eb..5f6e88d 100644
--- a/src/previous.js
+++ b/src/previous.js
@@ -4,8 +4,14 @@ angular.module('ct.ui.router.extras.previous', [ 'ct.ui.router.extras.core', 'ct
       var previous = null, lastPrevious = null, memos = {};
 
       $rootScope.$on("$transitionStart", function(evt, $transition$) {
-        lastPrevious = previous;
-        previous = $transition$.from;
+        var from = $transition$.from;
+        // Check if the fromState is navigable before tracking it.
+        // Root state doesn't get decorated with $$state().  Doh.
+        var fromState = from.state && from.state.$$state && from.state.$$state();
+        if (fromState && fromState.navigable) {
+          lastPrevious = previous;
+          previous = $transition$.from;
+        }
 
         $transition$.promise.then(commit).catch(revert);
         function commit() { lastPrevious = null; }
diff --git a/test/previousSpec.js b/test/previousSpec.js
index baaea7c..5cbb366 100644
--- a/test/previousSpec.js
+++ b/test/previousSpec.js
@@ -53,17 +53,26 @@ describe("$previousState", function () {
     $previousState = $get('$previousState');
   }));
 
+  // Test for #123
+  it("should not capture root state (or non-navigable states)", inject(function($rootScope) {
+    testGo("top", { entered: 'top' });
+    expect($previousState.get()).toBeNull();
+  }));
+
+
   describe('.go()', function () {
     it("should transition back to the previous state", function () {
       testGo("top.people.managerlist", { entered: pathFrom('top', 'top.people.managerlist') });
-      testGo("top.inv.storelist", { entered: pathFrom('top.inv', 'top.inv.storelist') , exited: pathFrom('top.people.managerlist', 'top.people') });
+      testGo("top.inv.storelist", { entered: pathFrom('top.inv', 'top.inv.storelist'), exited: pathFrom('top.people.managerlist', 'top.people') });
       $previousState.go();
       $q.flush();
       expect($state.current.name === "tabs.tabs2");
     });
+  });
 
+  describe('.get()', function() {
     // Test for #120
-    it("should go to previous state after another transition is cancelled", inject(function($rootScope) {
+    it("should not return current state, after a transition is cancelled", inject(function($rootScope) {
       testGo("top", { entered: 'top' });
       testGo("top.people.managerlist", { entered: ['top.people', 'top.people.managerlist'] });
 
@@ -71,8 +80,9 @@ describe("$previousState", function () {
       $rootScope.$on("$stateChangeStart", function(evt) { if (transitionNum++ === 0) { evt.preventDefault(); } });
 
       testGo("top.inv.storelist", undefined, { redirect: 'top.people.managerlist'}); // Cancelled, so we're still at original state
+
       expect($previousState.get().state.name).toBe("top");
-    }));
+    }))
   });
   
   describe('.memo()', function () {