@Test public void fetchInBackgroundWithNullAsOperation() { Throwable actual = thrownBy( () -> itemUiList.fetchInBackground( null ) ); assertThat( actual ) .hasMessage( OPERATION_MUST_NOT_BE_NULL ); }
public void fetchInBackground( FetchOperation operation ) { checkArgument( operation != null, OPERATION_MUST_NOT_BE_NULL ); backgroundProcessor.process( () -> fetch( operation ) ); }
ItemUiList { public void fetchInBackground( FetchOperation operation ) { checkArgument( operation != null, OPERATION_MUST_NOT_BE_NULL ); backgroundProcessor.process( () -> fetch( operation ) ); } }
ItemUiList { public void fetchInBackground( FetchOperation operation ) { checkArgument( operation != null, OPERATION_MUST_NOT_BE_NULL ); backgroundProcessor.process( () -> fetch( operation ) ); } protected  ItemUiList( ItemUiMap<T, U> itemUiMap, BackgroundProcessor backgroundProcessor ); }
ItemUiList { public void fetchInBackground( FetchOperation operation ) { checkArgument( operation != null, OPERATION_MUST_NOT_BE_NULL ); backgroundProcessor.process( () -> fetch( operation ) ); } protected  ItemUiList( ItemUiMap<T, U> itemUiMap, BackgroundProcessor backgroundProcessor ); boolean isTimelineEmpty(); void fetchInBackground( FetchOperation operation ); void fetch( FetchOperation operation ); void update(); }
ItemUiList { public void fetchInBackground( FetchOperation operation ) { checkArgument( operation != null, OPERATION_MUST_NOT_BE_NULL ); backgroundProcessor.process( () -> fetch( operation ) ); } protected  ItemUiList( ItemUiMap<T, U> itemUiMap, BackgroundProcessor backgroundProcessor ); boolean isTimelineEmpty(); void fetchInBackground( FetchOperation operation ); void fetch( FetchOperation operation ); void update();  }