Error: Could not resolve 'app.history' from state ' '

I am writing unit test which is using $stateProvider(the code is shown below for both the code and its test file).While executing this, it is giving error- "Error: Could not resolve 'app.history' from state ''".

$stateProvider
    .state('app',       { url: "/app",      templateUrl: "pages/app/index.html", controller: function($state)   {
        $state.go('app.history');
    }})
    .state('app.history', { url: "/history",    templateUrl: "pages/app/modules/History/partials/history.html"})

Unit test code -

describe("Unit tests for config.jst", function() {
  var $rootScope, $injector, $state;
  beforeEach(module('ui.router'));

  beforeEach(inject(function(_$rootScope_, _$state_, _$injector_, $templateCache) {
    $rootScope = _$rootScope_;
    $injector = _$injector_;
    $state = _$state_;

    $templateCache.put("pages/app/index.html", "");
    $templateCache.put("pages/app/modules/History/partials/history.html", "");
}));

describe("states", function() {
    var state = "app.history";
    it("verify state configuration", function() {
        //var config = $state.get(state);
        $state.go(state);
        $rootScope.$digest();
        //console.log($state);
        expect($state.current.name).to.be.equal(state);
    });
 });
});