'Error: Can't resolve all parameters for' error in Angular test module

I man having an issue in one of my test modules where I am getting the following error:

Failed: Can't resolve all parameters for CoreRequestClass: (?).
Error: Can't resolve all parameters for CoreRequestClass: (?).

Which is odd as as far as I can see I have included all required parameters to instantoate the module in the test.

Here is the service under test:

import { Headers } from "@angular/http";
import { AuthenticationService } from "./authentication.service";
import { objectHelper } from "../helpers/objectHelper";

export class CoreRequestClass {

    constructor(
        protected _authenticationService: AuthenticationService
    ) {

    }

    createAuthorizationHeader(token:Boolean = false) {
        let headers: Headers = new Headers();
        if(token) {
            headers.set('Authorization', 'Bearer ' + this._authenticationService.token);
        }

        return headers;
    }

    createURLVarString(urlVars: Object = {}) {
        let urlString: string = '',
            objLength = Object.keys(urlVars).length,
            i = 1;

        if(objLength !== 0) {
            urlString += '?';
            for(let [key, value] of objectHelper.loopThroughObject(urlVars)) {
                urlString += key + '=' + value;
            }
            if(i !== objLength) {
                urlString += '&';
                i++;
            }
        }

        return urlString;
    }
}

And the test module:

import { inject, async, TestBed } from "@angular/core/testing";
import { Router } from "@angular/router";
import { CoreRequestClass } from "../../services/CoreRequestClass";
import { AuthenticationService } from "../../services/authentication.service";
import { BaseRequestOptions, HttpModule, Http } from "@angular/http";
import { MockBackend } from "@angular/http/testing";

describe('Core Request Class', () => {
    let mockAuthenticateService = {
        navigate: jasmine.createSpy('navigate')
    };
    let router = {
        navigate: jasmine.createSpy('navigate')
    };
    beforeEach(() => {
        TestBed.configureTestingModule({
            providers: [
                CoreRequestClass,
                AuthenticationService,

                MockBackend,
                BaseRequestOptions,
                {
                    provide: Http,
                    useFactory: (backend, options) => new Http(backend, options),
                    deps: [MockBackend, BaseRequestOptions]
                },
                { provide: Router, useValue: router },
                { provide: AuthenticationService, useValue: mockAuthenticateService}
            ],
            imports: [
                HttpModule
            ]
        })
    });

    describe('createAuthorizationHeader', () => {
        it('should return headers with a token set', async(inject([AuthenticationService], (authenticationService) => {
            const token = 'token';
        })));
    });
});

I can't see why this spec won't be instantiating the module correctly. Can anyone see where i'm going wrong??

Thanks