Declaring slimLoadingBarService with let, you are constraining its scope to the beforeEach callback scope. Declare it with var, or better, declare it after the proper describe() block and set its content within beforeEach callback function:

describe("some describe statement" , function(){
    let slimLoadingBarService = null;

    beforeEach( () => {
        slimLoadingBarService=new SlimLoadingBarService();

    });

    it('should pass data to service', () => {
        spyOn(slimLoadingBarService,'start').and.callThrough();
       //testing code,if I remove the above service from my component, test runs fine
    });
});

Fixed by updating:

spyOn(component, 'changeTitle').and.callThrough();

to:

jasmine.createSpy('changeTitle').and.callThrough();

You can do this easily without using spyOnmethod.

Instead of that create spy object for your service and provide that spy object as the service in the providers array.

describe('Result component tests', () => {

  let fixture: ComponentFixture<ResultComponent>;
  let component: ResultComponent;

  let apiService: APIService;
  let spyApiService: jasmine.SpyObj<APIService>;

  let getRolesSubject;
  let mockResponse: ApiResponse =
    {
      code: '0',
      data: {
        permissionsList: [
          {
            orgRoles: 'Edit Access TRUE',
            roleType: 'OPTIONAL'
          }
        ]
      },
      message: '',
      status: 'success'
    };

  beforeEach(async(() => {
    getRolesSubject = new Subject();

    spyApiService = jasmine.createSpyObj('APIService', ['getRoles']);
    spyApiService.getRoles.and.returnValue(getRolesSubject.asObservable());

    TestBed.configureTestingModule({
      declarations: [ResultComponent],
      providers: [
        {provide: APIService, useValue: spyApiService},
      ],
      schemas: [NO_ERRORS_SCHEMA]
    }).compileComponents().then(() => {
      fixture = TestBed.createComponent(ResultComponent);
      component = fixture.componentInstance;

      apiService = TestBed.get(APIService);
    });
  }));


  it('Should invoke getRoles of api service when ...', () => {
    component.sendTask(model);
    getRolesSubject.next(mockResponse);
    expect(apiService.getRoles).toHaveBeenCalled();
  });

});

And I am using a subject to return values as observables from the service.

getRolesSubject.next(mockResponse);

Think that you have few methods inside the subscribe method. Now you can test them also.

Well, it's quite simple: you never initialize the variable component anywhere. So there's no object to spy upon, as the error message says, since component is undefined.

component = fixture.componentInstance;
onClickMock = spyOn(component, 'navigateBackToLanding').and.callThrough();

Can you show your TestBed.configureTestingModule({?

Make sure you create a spyObj for SkillAddService and add it to the providers.

beforeEach(waitForAsync(() => {
  // make sure you create this spy object with postSkillforMember public method to be mocked
  mockSkillAddService = jasmine.createSpyObj<SkillAddService>('SkillAddService', ['postSkillforMember']);
  TestBed.configureTestingModule({
    declarations: [...],
    // provide the mock instead of the real one
    providers: [{ provide: SkillAddService, useValue: mockSkillAddService }],
  }).compileComponents();
}));

 it('Testing addSkill() success', () => {
    // no need to spy anymore
    // spyOn(mockSkillAddService, 'postSkillforMember');
    component.addSkill();
    expect(component.showAlert).toBeFalsy();
    // can do:
    expect(mockSkillAddService.postSkillforMember).toHaveBeenCalled();
  });

Must inject the userServiceMock service, refer below code.

   beforeEach(module('user.controllers'));
   beforeEach(module('YOUR SERVICE MODULE'));

   beforeEach(inject(function($rootScope, $controller, userServiceMock) {
        scope = $rootScope.$new();
        controller = $controller('LoginController',{
            '$scope' : scope,
            '$state' : stateMock,
            'UserService' : userServiceMock
        });
    }));

According to the documentation :

You may also be able to get the service from the root injector via TestBed.get(). This is easier to remember and less verbose. But it only works when Angular injects the component with the service instance in the test's root injector.

So maybe you should try using the injector :

The safest way to get the injected service, the way that always works, is to get it from the injector of the component-under-test. The component injector is a property of the fixture's DebugElement.

authenticationservice = fixture.debugElement.injector.get(AuthenticationService)

EDIT Try injecting the dependency directly into your test

it('should login successfully', inject([AuthenticationService], (service: AuthenticationService) => {...}));

This is how I did it, hope it helps.

var Restangular;
beforeEach(inject(function( _Restangular_) {
    Restangular = _Restangular_;
    spyOn(Restangular, 'all').and.callThrough();
}));