fix($state): reloadOnSearch should not affect non-search param changes.

The handling of `reloadOnSearch: false` caused ui-router to avoid
reloading the state in more cases than it should. The designed and
documented behavior of this flag is to avoid state reload when the
URL search string changes. It was also avoiding state reload when
the URL path (or any non-search parameters to the state) changed,
and even when state reload was explicitly requested.

This change

- flips the name of shouldTriggerReload (and the accompanying guard
  boolean, skipTriggerReloadCheck) to match the direction of the
  logic: shouldSkipReload and allowSkipReloadCheck

- teaches shouldSkipReload to look at the types of the differing
  parameters, and only skip the reload if the only parameters that
  differ were search parameters

- pulls the test for options.reload to the front of the complex
  boolean expression. (I think calling $state.reload() explicitly
  should reload a state even if it has reloadOnSearch:false. But I
  don't understand exactly why the test for this was where it was, and
  maybe there's a good reason I'm missing. Also, if the behavior I
  favor is deemed correct, we could also achieve that by setting
  allowSkipReloadCheck=false for all truthy values of options.reload,
  namely, if options.reload===true, and then shouldSkipReload wouldn't
  even need to look at options. I left a comment about this in the
  source too and would appreciate feedback.)

Fixes angular-ui#1079. Helps with one of the cases broken in angular-ui#582.

src/state.js

@@ -954,7 +954,7 @@ function $StateProvider(   $urlRouterProvider,   $urlMatcherFactory) {
      *    have not changed, aka a reload of the same state. It differs from reloadOnSearch because you'd
      *    use this when you want to force a reload when *everything* is the same, including search params.
      *    if String, then will reload the state with the name given in reload, and any children.
-     *    if Object, then a stateObj is expected, will reload the state found in stateObj, and any chhildren.
+     *    if Object, then a stateObj is expected, will reload the state found in stateObj, and any children.
      *
      * @returns {promise} A promise representing the state of the new transition. See
      * {@link ui.router.state.$state#methods_go $state.go}.
@@ -1002,7 +1002,7 @@ function $StateProvider(   $urlRouterProvider,   $urlMatcherFactory) {
 
       // Starting from the root of the path, keep all levels that haven't changed
       var keep = 0, state = toPath[keep], locals = root.locals, toLocals = [];
-      var skipTriggerReloadCheck = false;
+      var allowSkipReloadCheck = true;
 
       if (!options.reload) {
         while (state && state === fromPath[keep] && state.ownParams.$$equals(toParams, fromParams)) {
@@ -1020,7 +1020,9 @@ function $StateProvider(   $urlRouterProvider,   $urlMatcherFactory) {
           throw new Error("No such reload state '" + (isString(options.reload) ? options.reload : options.reload.name) + "'");
         }
 
-        skipTriggerReloadCheck = true;
+        // Question for PR review: Why do we not reset this for options.reload === true?!
+        // (shouldSkipReload had an embedded check for options.reload but it wouldn't need it if we did this)
+        allowSkipReloadCheck = false;
 
         while (state && state === fromPath[keep] && state !== reloadState) {
           locals = toLocals[keep] = state.locals;
@@ -1034,7 +1036,7 @@ function $StateProvider(   $urlRouterProvider,   $urlMatcherFactory) {
       // TODO: We may not want to bump 'transition' if we're called from a location change
       // that we've initiated ourselves, because we might accidentally abort a legitimate
       // transition initiated from code?
-      if (!skipTriggerReloadCheck && shouldTriggerReload(to, from, locals, options)) {
+      if (allowSkipReloadCheck && shouldSkipReload(to, toParams, from, fromParams, locals, options)) {
         if (to.self.reloadOnSearch !== false) $urlRouter.update();
         $state.transition = null;
         return $q.when($state.current);
@@ -1429,11 +1431,43 @@ function $StateProvider(   $urlRouterProvider,   $urlMatcherFactory) {
     return $state;
   }
 
-  function shouldTriggerReload(to, from, locals, options) {
-    if (to === from && ((locals === from.locals && !options.reload) || (to.self.reloadOnSearch === false))) {
+  function shouldSkipReload(to, toParams, from, fromParams, locals, options) {
+    // If reload was not explicitly requested
+    // and we're transitioning to the same state we're already in
+    // and    the locals didn't change
+    //     or they changed in a way that doesn't merit reloading
+    //        (reloadOnParams:false, or reloadOnSearch.false and only search params changed)
+    // Then skip the reload.
+    // NB: If we skip the reload, $stateParams does not get updated. So people have to manage
+    // $location.search() entirely manually, not via $stateParams, if using reloadOnSearch: false.
+    if (!options.reload && to === from && (locals === from.locals || (to.self.reloadOnSearch === false && onlySearchParamsChanged(from, fromParams, to, toParams)))) {
       return true;
     }
   }
+
+  function noteNonSearchParams(params, nonSearchParamsHash) {
+    for (var key in params) {
+      if (key.indexOf('$$') !== 0 && params[key].location !== 'search') {
+        nonSearchParamsHash[key] = true;
+      }
+    }
+  }
+
+  function onlySearchParamsChanged(from, fromParams, to, toParams) {
+    // Identify whether all the parameters that differ between `fromParams` and `toParams` were search params.
+    // Return true if the only differences were in search params, false if there were differences in other params.
+    // Algorithm: build a set of keys of params that are not search params.
+    // Walk that set, comparing the actual values between the fromParams and toParams.
+    var nonSearchParams = {};
+    noteNonSearchParams(from.params, nonSearchParams);
+    noteNonSearchParams(to.params, nonSearchParams);
+    for (var key in nonSearchParams) {
+      if (fromParams[key] !== toParams[key]) {
+        return false;
+      }
+    }
+    return true;
+  }
 }
 
 angular.module('ui.router.state')

test/stateSpec.js

@@ -29,6 +29,7 @@ describe('state', function () {
       HH = { parent: H },
       HHH = {parent: HH, data: {propA: 'overriddenA', propC: 'propC'} },
       RS = { url: '^/search?term', reloadOnSearch: false },
+      RSP = { url: '^/:doReload/search?term', reloadOnSearch: false },
       OPT = { url: '/opt/:param', params: { param: "100" } },
       OPT2 = { url: '/opt2/:param2/:param3', params: { param3: "300", param4: "400" } },
       AppInjectable = {};
@@ -55,6 +56,7 @@ describe('state', function () {
       .state('OPT', OPT)
       .state('OPT.OPT2', OPT2)
       .state('RS', RS)
+      .state('RSP', RSP)
 
       .state('home', { url: "/" })
       .state('home.item', { url: "front/:id" })
@@ -212,7 +214,20 @@ describe('state', function () {
       });
       $q.flush();
       expect($location.search()).toEqual({term: 'hello'});
-      expect(called).toBeFalsy();        
+      expect(called).toBeFalsy();
+    }));
+
+    it('does trigger state change for path params even if reloadOnSearch is false', inject(function ($state, $q, $location, $rootScope){
+      initStateTo(RSP, { doReload: 'foo' });
+      expect($state.params.doReload).toEqual('foo');
+      var called;
+      $rootScope.$on('$stateChangeStart', function (ev, to, toParams, from, fromParams) {
+        called = true
+      });
+      $state.transitionTo(RSP, { doReload: 'bar' });
+      $q.flush();
+      expect($state.params.doReload).toEqual('bar');
+      expect(called).toBeTruthy();
     }));
 
     it('ignores non-applicable state parameters', inject(function ($state, $q) {
@@ -940,6 +955,7 @@ describe('state', function () {
         'OPT',
         'OPT.OPT2',
         'RS',
+        'RSP',
         'about',
         'about.person',
         'about.person.item',