test("Informs about disconnected kernels, allows reconnection", async () => {
   const state$ = {
     value: {
       core: stateModule.makeStateRecord({
         kernelRef: "fake",
         entities: stateModule.makeEntitiesRecord({
           contents: stateModule.makeContentsRecord({
             byRef: Immutable.Map({
               fakeContent: stateModule.makeNotebookContentRecord()
             })
           }),
           kernels: stateModule.makeKernelsRecord({
             byRef: Immutable.Map({
               fake: stateModule.makeRemoteKernelRecord({
                 channels: null,
                 status: "not connected"
               })
             })
           })
         })
       }),
       app: {
         notificationSystem: { addNotification: jest.fn() }
       }
     }
   };
   const action$ = ActionsObservable.of(
     actions.executeCell({ id: "first", contentRef: "fakeContentRef" })
   );
   const responses = await executeCellEpic(action$, state$)
     .pipe(toArray())
     .toPromise();
   expect(responses).toEqual([]);
 });

    mergeMap((action: ExecuteCell | ExecuteFocusedCell) => {
      if (action.type === actions.EXECUTE_FOCUSED_CELL) {
        const contentRef = action.payload.contentRef;
        const state = state$.value;
        const model = selectors.model(state, { contentRef });
        // If it's not a notebook, we shouldn't be here
        if (!model || model.type !== "notebook") {
          return empty();
        }

        const id = model.cellFocused;

        if (!id) {
          throw new Error("attempted to execute without an id");
        }
        return of(
          actions.executeCell({ id, contentRef: action.payload.contentRef })
        );
      }
      return of(action);
    }),

 ...codeCellIds.map((id: CellId) =>
   actions.executeCell({ id, contentRef: action.payload.contentRef })