AngularJS testing error: Unknown provider: $_httpBackend_Provider <- $_httpBackend_ - jasmine

Question

I am attempting to test an AngularJS controller with a Jasmine unit test spec file. My approach is to use $httpBacked, in the following test:
describe('SubmissionsController', function() {
var minimal_mock_response = [ { id: 1 } ];
var scope, routeParams, $httpBackend;
beforeEach(module('submissionServices'));
beforeEach(inject(function($_httpBackend_, $rootScope) {
scope = $rootScope.$new();
$httpBackend = $_httpBackend_;
$httpBackend.expectGET('/submissions').respond(minimal_mock_response);
routeParams = {};
}));
it('passes a trivial test', function() {
expect(true).toBe(true);
});
});
I inserted the expect(true).toBe(true) just to get the test to execute and fail, even though it does not touch the angular controller. When I I attempt to run the test with jasmine-headless-webkit, I receive the following error:
jasmine-headless-webkit spec/javascripts/SubmissionsControllerSpec.js
Running Jasmine specs...
F
FAIL: 1 test, 1 failure, 0.011 secs.
Submissions controllers SubmissionsController passes a trivial test. (XXX/spec/javascripts/SubmissionsControllerSpec.js:18)
Error: Unknown provider: $_httpBackend_Provider <- $_httpBackend_
Test ordering seed: --seed 9254
Are there any hints on how I can correct this error and make the trivial test execute?

Answer 1

Enclosing service names with underscores has some benefit.
From your code, I can see that you probably wanted to save the reference to $httpBackend. This is how you wanted to do. The placement of underscore was one off.
beforeEach(inject(function(_$httpBackend_, $rootScope) {
scope = $rootScope.$new();
$httpBackend = _$httpBackend_;
...
Angular is smart enough to remove underscores and returns $httpBackend back to you, and you can save it to your own $httpBackend.

Answer 2

I believe this is because you're injecting the wrong service. It doesn't know what $_httpBackend_ is. You should be able to just do this:
beforeEach(inject(function($httpBackend, $rootScope) {
scope = $rootScope.$new();
$httpBackend.expectGET('/submissions').respond(minimal_mock_response);
routeParams = {};
}));
If you want to get a reference to the $httpBackend service once and store that as $httpBackend, ghiden's answer is the way to go.