Testing a simple AngularJS service using Jasmine

Question

I have a simple service that I am trying to unit test. No matter what I try, either the searchService is an unknown provider, or service is null (which oddly enough won't cause my test to fail!!).

Anyone have an insight on what I might be doing wrong??

angular.module('app').service('searchService', function( $q, _ ) { // _ is lodash

  var cache = [
    {
      id: "current",
      name: "Current",
      description: "Search current data"
    },
    {
      id: "historical",
      name: "Historical",
      description: "Search historical data"
    }
  ];

  this.getSearchOptions = function() {
    var deferred = $q.defer();
    deferred.resolve( angular.copy( cache ) );
    return( deferred.promise );
  };

  this.getSearchOptionsByID = function( id ) {
    var deferred = $q.defer();
    var searchOption = _.findWithProperty( cache, "id", id );

    if ( searchOption ) {
      deferred.resolve( angular.copy( searchOption ) );
    } else {
      deferred.reject();
    }
    return( deferred.promise );
   };
  }
);

I am trying to create a unit test that loads in the searchService so I can check the cached values:

describe("Unit: Testing Services", function() {
  describe("Search Service:", function() {
    var service = null;

    beforeEach(function() {
      angular.module('app').service('_');
    });
    // I've also tried the commented out code below
    //beforeEach(inject(function(searchService) {
    //this.service = searchService;
    //}));
    //it('should contain an searchService', invoke(function(service) {

    it('should contain an searchService', function(searchService) {
      expect(searchService).not.to.equal(null);
    });

    it('should contain two search options', function(searchService) {
      expect(searchService.getSearchOptions()).to.equal(2);
    });
  });
});

Solution

The following should work for a service without parameter, maybe this can be a starting point:

describe("Unit: Testing Services", function() {
    describe("Search Service:", function() {

        beforeEach(function() {
            angular.module('app');
        });

        it('should contain a searchService',
           inject(function(searchService) {
                expect(searchService).not.to.equal(null);
        }));

        it('should contain two search options',
            inject(function(searchService) {
                expect(searchService.getSearchOptions()).to.equal(2);
        }));

   });
});

(You can also have a look here: How do I test an AngularJS service with Jasmine?)