XState Viz: https://xstate.js.org/viz/?gist=7745fd94ff4b72002e2a422ef2144db8

machine.js

  // Available variables:
  // - Machine
  // - interpret
  // - assign
  // - send
  // - sendParent
  // - spawn
  // - raise
  // - actions
  // - XState (all XState exports)
  
  const increment = key => context => context[key]++
  const decrement = key => context => context[key]--
  
  const cartActions = {
    ADD_FACILITY: {
      target: 'not-empty',
      actions: increment('addFacility'),
    },
    REMOVE_FACILITY: {
      target: 'not-empty',
      actions: decrement('addFacility'),
    },
    ADD_ADDON: {
      target: 'not-empty',
      actions: increment('addAddon'),
    },
    CANCEL_ADDON: {
      target: 'not-empty',
      actions: decrement('addAddon'),
    },
    CANCEL_ALL: {
      target: 'empty',
    },
  }
  
  const fetchMachine = Machine({
    id: 'cart',
    initial: 'empty',
    context: {
      addFacility: 0,
      addAddon: 0,
      cancelAddon: 0,
      reactivateAddon: 0,
      switchAddon: 0,
    },
    states: {
      empty: {
        entry: 'clearCart',
        on: {
          ...cartActions,
        }
      },
      'not-empty': {
        on: {
          EMPTY: {
            target: 'empty',
            cond: 'isEmpty',
          },
          CHECKOUT: {
            target: 'empty',
            cond: 'notEmpty',
          },
          ...cartActions,
        },
        meta: {
          test: 'test',
        },
      },
    },
  },
  {
    actions: {
      clearCart: context => Object.keys(context)
        .forEach(k => context[k] = 0),
    },
    guards: {
      isEmpty: context => Object.keys(context).reduce((acc, key) => acc + context[key], 0) < 1,
      notEmpty: context => Object.keys(context).reduce((acc, key) => acc + context[key], 0) > 0,
    }
  });