inject gives throws Error: [ng:areq] Argument 'fn' is not a function, got string

I am new to AngularJS and i try to develop an AngularJS app together with coffeescript in a testdriven way and cannot get inject to work. For creating the project i set it up using yeoman:

yo angular --coffee someapp

Then i created the test and the provider using

yo angular:provider testProvider

And here is the unittest for the provider i'm trying to test:

 someApi = {'test': 'gets assigned'}

  # load the service's module
  beforeEach () ->
    console.log('service module')
    module 'SomeApp', (someApiProvider) ->
        someApiProvider.set_salutation("Hey Guys")

  beforeEach () ->
    console.log('inject')
    inject( 
      ('_someApi_') ->
    )
    console.log('after inject')

  it 'should do something', ->
    expect(!!soeaidApi).toBe true

I tried different versions of the inject call like:

inject()

inject(
  (_someApi_) ->
      someApi = _someApi_
) 

inject((_httpBackend_) -> )

and many more, but i do not see the 'after inject' in the log and the output of karma stays the same:

PhantomJS 1.9.8 (Linux) Service: someApi should do something FAILED
    Error: [ng:areq] Argument 'fn' is not a function, got string
    http://ift.tt/1Mle2kZ
        at assertArg ($PROJ_ROOT/angular_app/bower_components/angular/angular.js:1580)
        at assertArgFn ($PROJ_ROOT/angular_app/bower_components/angular/angular.js:1591)
        at annotate ($PROJ_ROOT/angular_app/bower_components/angular/angular.js:3474)
        at $PROJ_ROOT/angular_app/bower_components/angular-mocks/angular-mocks.js:2147
        at invoke ($PROJ_ROOT/angular_app/bower_components/angular/angular.js:4163)
        at $PROJ_ROOT/angular_app/bower_components/angular/angular.js:4007
        at forEach ($PROJ_ROOT/angular_app/bower_components/angular/angular.js:323)
        at createInjector ($PROJ_ROOT/angular_app/bower_components/angular/angular.js:4007)
        at workFn ($PROJ_ROOT/angular_app/bower_components/angular-mocks/angular-mocks.js:2353)

But if i comment out the inject line i see the 'after inject' log (obviously). What am i missing, do i call inject in a wrong way, and if yes how to do it right? And what does the error log mean by the 'fn' argument?