mergeMap((action: actions.FetchContentFulfilled) => {
      const state: AppState = state$.value;

      const contentRef = action.payload.contentRef;

      const content = selectors.content(state, { contentRef });

      if (
        !content ||
        content.type !== "notebook" ||
        content.model.type !== "notebook"
      ) {
        // This epic only handles notebook content
        return empty();
      }

      const filepath = content.filepath;
      const notebook = content.model.notebook;

      const { cwd, kernelSpecName } = extractNewKernel(filepath, notebook);

      return of(
        actions.launchKernelByName({
          kernelSpecName,
          cwd,
          kernelRef: action.payload.kernelRef,
          selectNextKernel: true,
          contentRef: action.payload.contentRef
        })
      );
    })

  test("launches remote kernels", async function() {
    const contentRef = "fakeContentRef";
    const kernelRef = "fake";
    const value = {
      app: stateModule.makeAppRecord({
        host: stateModule.makeJupyterHostRecord({
          type: "jupyter",
          token: "eh",
          basePath: "http://localhost:8888/"
        }),
        notificationSystem: { addNotification: jest.fn() }
      }),
      comms: stateModule.makeCommsRecord(),
      config: Immutable.Map({}),
      core: stateModule.makeStateRecord({
        kernelRef: "fake",
        entities: stateModule.makeEntitiesRecord({
          contents: stateModule.makeContentsRecord({
            byRef: Immutable.Map({
              fakeContentRef: stateModule.makeNotebookContentRecord()
            })
          }),
          kernels: stateModule.makeKernelsRecord({
            byRef: Immutable.Map({
              fake: stateModule.makeRemoteKernelRecord({
                type: "websocket",
                channels: new Subject<any>(),
                kernelSpecName: "fancy",
                id: "0"
              })
            })
          })
        })
      })
    };
    const state$ = new StateObservable(
      new Subject<stateModule.AppState>(),
      value
    );
    const action$ = ActionsObservable.of(
      actions.launchKernelByName({
        contentRef,
        kernelRef,
        kernelSpecName: "fancy",
        cwd: "/",
        selectNextKernel: true
      })
    );

    const responseActions = await coreEpics
      .launchWebSocketKernelEpic(action$, state$)
      .pipe(toArray())
      .toPromise();

    expect(responseActions).toEqual([
      {
        type: "LAUNCH_KERNEL_SUCCESSFUL",
        payload: {
          contentRef,
          kernelRef,
          selectNextKernel: true,
          kernel: {
            info: null,
            sessionId: "1",
            type: "websocket",
            channels: expect.any(Subject),
            kernelSpecName: "fancy",
            cwd: "/",
            id: "0"
          }
        }
      }
    ]);
  });

    concatMap((action: actions.RestartKernel | actions.NewKernelAction) => {
      const state = state$.value;
      const oldKernelRef = action.payload.kernelRef;
      const notificationSystem = selectors.notificationSystem(state);

      if (!oldKernelRef) {
        notificationSystem.addNotification({
          title: "Failure to Restart",
          message: "Unable to restart kernel, please select a new kernel.",
          dismissible: true,
          position: "tr",
          level: "error"
        });
        return empty();
      }

      const oldKernel = selectors.kernel(state, { kernelRef: oldKernelRef });

      if (!oldKernelRef || !oldKernel) {
        notificationSystem.addNotification({
          title: "Failure to Restart",
          message: "Unable to restart kernel, please select a new kernel.",
          dismissible: true,
          position: "tr",
          level: "error"
        });

        // TODO: Wow do we need to send notifications through our store for
        // consistency
        return empty();
      }

      const newKernelRef = kernelRefGenerator();
      const initiatingContentRef = action.payload.contentRef;

      // TODO: Incorporate this into each of the launchKernelByName
      //       actions...
      //       This only mirrors the old behavior of restart kernel (for now)
      notificationSystem.addNotification({
        title: "Kernel Restarting...",
        message: `Kernel ${oldKernel.kernelSpecName ||
          "unknown"} is restarting.`,
        dismissible: true,
        position: "tr",
        level: "success"
      });

      const kill = actions.killKernel({
        restarting: true,
        kernelRef: oldKernelRef
      });

      const relaunch = actions.launchKernelByName({
        kernelSpecName: oldKernel.kernelSpecName,
        cwd: oldKernel.cwd,
        kernelRef: newKernelRef,
        selectNextKernel: true,
        contentRef: initiatingContentRef
      });

      const awaitKernelReady = action$.pipe(
        ofType(actions.LAUNCH_KERNEL_SUCCESSFUL),
        filter(
          (action: actions.NewKernelAction | actions.RestartKernel) =>
            action.payload.kernelRef === newKernelRef
        ),
        take(1),
        timeout(60000), // If kernel doesn't come up within this interval we will abort follow-on actions.
        concatMap(() => {
          const restartSuccess = actions.restartKernelSuccessful({
            kernelRef: newKernelRef,
            contentRef: initiatingContentRef
          });

          if (
            (action as actions.RestartKernel).payload.outputHandling ===
            "Run All"
          ) {
            return of(
              restartSuccess,
              actions.executeAllCells({ contentRef: initiatingContentRef })
            );
          } else {
            return of(restartSuccess);
          }
        }),
        catchError(error => {
          return of(
            actions.restartKernelFailed({
              error,
              kernelRef: newKernelRef,
              contentRef: initiatingContentRef
            })
          );
        })
      );

      return merge(of(kill, relaunch), awaitKernelReady);
    })