Angular testing,You may need an appropriate loader to handle this file type. @import '../../sass/conf/conf';

When i carry out the angular test of the angularjs，i caught this error You may need an appropriate loader to handle this file type. | @import '../../sass/conf/conf'; | @import '../../components/baMsgCenter/baMsgCenter'; | at karma-shim.js:174003

//webpack.test.js
var webpack = require('webpack');
var helpers = require('./config/helpers');
const ExtractTextPlugin = require('extract-text-webpack-plugin');
module.exports = {
  devtool: 'inline-source-map',

  resolve: {
    extensions: ['.ts', '.js']
  },

  entry: {
  },

  module: {
    rules: [
      {
        test: /\.ts$/,
        loaders: [
          {
            loader: 'awesome-typescript-loader',
            options: { configFileName: helpers.root('src', 'tsconfig.json') }
          }, 'angular2-template-loader'
        ]
      },
      {
        test: /\.html$/,
        loader: 'html-loader'

      },
      {
        test: /\.(png|jpe?g|gif|svg|woff|woff2|ttf|eot|ico)$/,
        loader: 'null-loader'
      },
      {
        test: /\.css$/,
        exclude: helpers.root('src', 'app'),
        loader: 'null-loader'
      },
      {
        test: /\.css$/,
        include: helpers.root('src', 'app'),
        loader: 'raw-loader'
      }

    ]
  },

  plugins: [
    new webpack.ContextReplacementPlugin(
      // The (\\|\/) piece accounts for path separators in *nix and Windows
      /angular(\\|\/)core(\\|\/)(esm(\\|\/)src|src)(\\|\/)linker/,
      helpers.root('./src'), // location of your src
      {} // a map of your routes
    )
  ]
}

//strategyTables.component.spec.ts
describe('StrategyTables test',()=> {
  var comp:StrategyTables;
  var fixture:ComponentFixture<StrategyTables>;
  var de: DebugElement;
  var el: HTMLElement;


  beforeEach(async(()=>{
    TestBed.configureTestingModule({
      declarations:[StrategyTables],
      imports:[
        FormsModule,
        PaginationModule,
        CommonModule,
        NgaModule,
        Ng2SmartTableModule,
        DropdownModule,
        ModalModule
        //StrategysModule
      ],
      providers:[
        {provide:StrategyTablesService,useClass:MockStrategyTablesService},
        {provide:Router,useClass:RouterStub},
        {provide:Location,useClass:MockLocation}
      ]
    }).compileComponents();
  }));

  beforeEach(()=>{
    fixture = TestBed.createComponent(StrategyTables);
    comp = fixture.componentInstance;
  });

  it('test function',()=>{
    comp.getById(1);
    expect(comp.detail.name).toEqual("aaa");
  });
});

I don't know what result to it,and how to fix it.Does someone has encountered such problems, or know how to solve it?