如何为bellow控制器编写单元测试用例。我对angularjs完全陌生，我必须解决这个问题。请引导我

angular.module('ourAppApp')
.controller('MainCtrl', function($scope,apiFac) {
    $scope.displayCity = false;
    $scope.displayWeather = false;
    $scope.today = new Date();
    $scope.searchCity = function(){
        if($scope.cityInput != ""){ 
          apiFac.searchCity($scope.cityInput).then(function(response){
            $scope.searchResponse = response;
            $scope.displayCity = true;
          })
        }   
    }
    $scope.getcitydetails = function(item){
      $scope.cityInput = "";
      $scope.displayCity = false;
      $scope.selectedCity = item;
      apiFac.weatherReport(item.woeid).then(function(response){
        $scope.weatherResponse = response;
        $scope.displayCity = false;
        $scope.displayWeather = true;
      })
    }
})