xstate/dist/xstate.development.esm.js

Finite State Machines and Statecharts for the Modern Web.

export { createEmptyActor, fromCallback, fromEventObservable, fromObservable, fromPromise, fromTransition } from '../actors/dist/xstate-actors.development.esm.js';
import { S as STATE_DELIMITER, m as mapValues, t as toArray, f as formatTransitions, a as toTransitionConfigArray, b as formatTransition, N as NULL_EVENT, e as evaluateGuard, c as createInvokeId, g as getDelayedTransitions, d as formatInitialTransition, h as getCandidates, r as resolveStateValue, i as getAllStateNodes, j as getStateNodes, k as createMachineSnapshot, l as isInFinalState, n as macrostep, o as transitionNode, p as resolveActionsAndContext, q as createInitEvent, s as microstep, u as getInitialStateNodes, v as toStatePath, w as isStateId, x as getStateNodeByPath, y as getPersistedSnapshot, z as resolveReferencedActor, A as createActor, $ as $$ACTOR_TYPE } from './raise-03a786f4.development.esm.js';
export { B as Actor, I as __unsafe_getAllOwnEventDescriptors, E as and, M as cancel, A as createActor, j as getStateNodes, C as interpret, D as isMachineSnapshot, J as matchesState, F as not, G as or, K as pathToStateValue, O as raise, P as spawnChild, H as stateIn, Q as stop, R as stopChild, L as toObserver } from './raise-03a786f4.development.esm.js';
import { a as assign } from './log-f64de12b.development.esm.js';
export { S as SpecialTargets, a as assign, e as emit, b as enqueueActions, f as forwardTo, l as log, s as sendParent, c as sendTo } from './log-f64de12b.development.esm.js';
import '../dev/dist/xstate-dev.development.esm.js';

class SimulatedClock {
  constructor() {
    this.timeouts = new Map();
    this._now = 0;
    this._id = 0;
    this._flushing = false;
    this._flushingInvalidated = false;
  }
  now() {
    return this._now;
  }
  getId() {
    return this._id++;
  }
  setTimeout(fn, timeout) {
    this._flushingInvalidated = this._flushing;
    const id = this.getId();
    this.timeouts.set(id, {
      start: this.now(),
      timeout,
      fn
    });
    return id;
  }
  clearTimeout(id) {
    this._flushingInvalidated = this._flushing;
    this.timeouts.delete(id);
  }
  set(time) {
    if (this._now > time) {
      throw new Error('Unable to travel back in time');
    }
    this._now = time;
    this.flushTimeouts();
  }
  flushTimeouts() {
    if (this._flushing) {
      this._flushingInvalidated = true;
      return;
    }
    this._flushing = true;
    const sorted = [...this.timeouts].sort(([_idA, timeoutA], [_idB, timeoutB]) => {
      const endA = timeoutA.start + timeoutA.timeout;
      const endB = timeoutB.start + timeoutB.timeout;
      return endB > endA ? -1 : 1;
    });
    for (const [id, timeout] of sorted) {
      if (this._flushingInvalidated) {
        this._flushingInvalidated = false;
        this._flushing = false;
        this.flushTimeouts();
        return;
      }
      if (this.now() - timeout.start >= timeout.timeout) {
        this.timeouts.delete(id);
        timeout.fn.call(null);
      }
    }
    this._flushing = false;
  }
  increment(ms) {
    this._now += ms;
    this.flushTimeouts();
  }
}

const cache = new WeakMap();
function memo(object, key, fn) {
  let memoizedData = cache.get(object);
  if (!memoizedData) {
    memoizedData = {
      [key]: fn()
    };
    cache.set(object, memoizedData);
  } else if (!(key in memoizedData)) {
    memoizedData[key] = fn();
  }
  return memoizedData[key];
}

const EMPTY_OBJECT = {};
const toSerializableAction = action => {
  if (typeof action === 'string') {
    return {
      type: action
    };
  }
  if (typeof action === 'function') {
    if ('resolve' in action) {
      return {
        type: action.type
      };
    }
    return {
      type: action.name
    };
  }
  return action;
};
class StateNode {
  constructor(
  /**
   * The raw config used to create the machine.
   */
  config, options) {
    this.config = config;
    /**
     * The relative key of the state node, which represents its location in the overall state value.
     */
    this.key = void 0;
    /**
     * The unique ID of the state node.
     */
    this.id = void 0;
    /**
     * The type of this state node:
     *
     *  - `'atomic'` - no child state nodes
     *  - `'compound'` - nested child state nodes (XOR)
     *  - `'parallel'` - orthogonal nested child state nodes (AND)
     *  - `'history'` - history state node
     *  - `'final'` - final state node
     */
    this.type = void 0;
    /**
     * The string path from the root machine node to this node.
     */
    this.path = void 0;
    /**
     * The child state nodes.
     */
    this.states = void 0;
    /**
     * The type of history on this state node. Can be:
     *
     *  - `'shallow'` - recalls only top-level historical state value
     *  - `'deep'` - recalls historical state value at all levels
     */
    this.history = void 0;
    /**
     * The action(s) to be executed upon entering the state node.
     */
    this.entry = void 0;
    /**
     * The action(s) to be executed upon exiting the state node.
     */
    this.exit = void 0;
    /**
     * The parent state node.
     */
    this.parent = void 0;
    /**
     * The root machine node.
     */
    this.machine = void 0;
    /**
     * The meta data associated with this state node, which will be returned in State instances.
     */
    this.meta = void 0;
    /**
     * The output data sent with the "xstate.done.state._id_" event if this is a final state node.
     */
    this.output = void 0;
    /**
     * The order this state node appears. Corresponds to the implicit document order.
     */
    this.order = -1;
    this.description = void 0;
    this.tags = [];
    this.transitions = void 0;
    this.always = void 0;
    this.parent = options._parent;
    this.key = options._key;
    this.machine = options._machine;
    this.path = this.parent ? this.parent.path.concat(this.key) : [];
    this.id = this.config.id || [this.machine.id, ...this.path].join(STATE_DELIMITER);
    this.type = this.config.type || (this.config.states && Object.keys(this.config.states).length ? 'compound' : this.config.history ? 'history' : 'atomic');
    this.description = this.config.description;
    this.order = this.machine.idMap.size;
    this.machine.idMap.set(this.id, this);
    this.states = this.config.states ? mapValues(this.config.states, (stateConfig, key) => {
      const stateNode = new StateNode(stateConfig, {
        _parent: this,
        _key: key,
        _machine: this.machine
      });
      return stateNode;
    }) : EMPTY_OBJECT;
    if (this.type === 'compound' && !this.config.initial) {
      throw new Error(`No initial state specified for compound state node "#${this.id}". Try adding { initial: "${Object.keys(this.states)[0]}" } to the state config.`);
    }

    // History config
    this.history = this.config.history === true ? 'shallow' : this.config.history || false;
    this.entry = toArray(this.config.entry).slice();
    this.exit = toArray(this.config.exit).slice();
    this.meta = this.config.meta;
    this.output = this.type === 'final' || !this.parent ? this.config.output : undefined;
    this.tags = toArray(config.tags).slice();
  }

  /** @internal */
  _initialize() {
    this.transitions = formatTransitions(this);
    if (this.config.always) {
      this.always = toTransitionConfigArray(this.config.always).map(t => formatTransition(this, NULL_EVENT, t));
    }
    Object.keys(this.states).forEach(key => {
      this.states[key]._initialize();
    });
  }

  /**
   * The well-structured state node definition.
   */
  get definition() {
    return {
      id: this.id,
      key: this.key,
      version: this.machine.version,
      type: this.type,
      initial: this.initial ? {
        target: this.initial.target,
        source: this,
        actions: this.initial.actions.map(toSerializableAction),
        eventType: null,
        reenter: false,
        toJSON: () => ({
          target: this.initial.target.map(t => `#${t.id}`),
          source: `#${this.id}`,
          actions: this.initial.actions.map(toSerializableAction),
          eventType: null
        })
      } : undefined,
      history: this.history,
      states: mapValues(this.states, state => {
        return state.definition;
      }),
      on: this.on,
      transitions: [...this.transitions.values()].flat().map(t => ({
        ...t,
        actions: t.actions.map(toSerializableAction)
      })),
      entry: this.entry.map(toSerializableAction),
      exit: this.exit.map(toSerializableAction),
      meta: this.meta,
      order: this.order || -1,
      output: this.output,
      invoke: this.invoke,
      description: this.description,
      tags: this.tags
    };
  }

  /** @internal */
  toJSON() {
    return this.definition;
  }

  /**
   * The logic invoked as actors by this state node.
   */
  get invoke() {
    return memo(this, 'invoke', () => toArray(this.config.invoke).map((invokeConfig, i) => {
      const {
        src,
        systemId
      } = invokeConfig;
      const resolvedId = invokeConfig.id ?? createInvokeId(this.id, i);
      const resolvedSrc = typeof src === 'string' ? src : `xstate.invoke.${createInvokeId(this.id, i)}`;
      return {
        ...invokeConfig,
        src: resolvedSrc,
        id: resolvedId,
        systemId: systemId,
        toJSON() {
          const {
            onDone,
            onError,
            ...invokeDefValues
          } = invokeConfig;
          return {
            ...invokeDefValues,
            type: 'xstate.invoke',
            src: resolvedSrc,
            id: resolvedId
          };
        }
      };
    }));
  }

  /**
   * The mapping of events to transitions.
   */
  get on() {
    return memo(this, 'on', () => {
      const transitions = this.transitions;
      return [...transitions].flatMap(([descriptor, t]) => t.map(t => [descriptor, t])).reduce((map, [descriptor, transition]) => {
        map[descriptor] = map[descriptor] || [];
        map[descriptor].push(transition);
        return map;
      }, {});
    });
  }
  get after() {
    return memo(this, 'delayedTransitions', () => getDelayedTransitions(this));
  }
  get initial() {
    return memo(this, 'initial', () => formatInitialTransition(this, this.config.initial));
  }

  /** @internal */
  next(snapshot, event) {
    const eventType = event.type;
    const actions = [];
    let selectedTransition;
    const candidates = memo(this, `candidates-${eventType}`, () => getCandidates(this, eventType));
    for (const candidate of candidates) {
      const {
        guard
      } = candidate;
      const resolvedContext = snapshot.context;
      let guardPassed = false;
      try {
        guardPassed = !guard || evaluateGuard(guard, resolvedContext, event, snapshot);
      } catch (err) {
        const guardType = typeof guard === 'string' ? guard : typeof guard === 'object' ? guard.type : undefined;
        throw new Error(`Unable to evaluate guard ${guardType ? `'${guardType}' ` : ''}in transition for event '${eventType}' in state node '${this.id}':\n${err.message}`);
      }
      if (guardPassed) {
        actions.push(...candidate.actions);
        selectedTransition = candidate;
        break;
      }
    }
    return selectedTransition ? [selectedTransition] : undefined;
  }

  /**
   * All the event types accepted by this state node and its descendants.
   */
  get events() {
    return memo(this, 'events', () => {
      const {
        states
      } = this;
      const events = new Set(this.ownEvents);
      if (states) {
        for (const stateId of Object.keys(states)) {
          const state = states[stateId];
          if (state.states) {
            for (const event of state.events) {
              events.add(`${event}`);
            }
          }
        }
      }
      return Array.from(events);
    });
  }

  /**
   * All the events that have transitions directly from this state node.
   *
   * Excludes any inert events.
   */
  get ownEvents() {
    const events = new Set([...this.transitions.keys()].filter(descriptor => {
      return this.transitions.get(descriptor).some(transition => !(!transition.target && !transition.actions.length && !transition.reenter));
    }));
    return Array.from(events);
  }
}

const STATE_IDENTIFIER = '#';
class StateMachine {
  constructor(
  /**
   * The raw config used to create the machine.
   */
  config, implementations) {
    this.config = config;
    /**
     * The machine's own version.
     */
    this.version = void 0;
    this.schemas = void 0;
    this.implementations = void 0;
    /** @internal */
    this.__xstatenode = true;
    /** @internal */
    this.idMap = new Map();
    this.root = void 0;
    this.id = void 0;
    this.states = void 0;
    this.events = void 0;
    /**
     * @deprecated an internal property that was acting as a "phantom" type, it's not used by anything right now but it's kept around for compatibility reasons
     **/
    this.__TResolvedTypesMeta = void 0;
    this.id = config.id || '(machine)';
    this.implementations = {
      actors: implementations?.actors ?? {},
      actions: implementations?.actions ?? {},
      delays: implementations?.delays ?? {},
      guards: implementations?.guards ?? {}
    };
    this.version = this.config.version;
    this.schemas = this.config.schemas;
    this.transition = this.transition.bind(this);
    this.getInitialSnapshot = this.getInitialSnapshot.bind(this);
    this.getPersistedSnapshot = this.getPersistedSnapshot.bind(this);
    this.restoreSnapshot = this.restoreSnapshot.bind(this);
    this.start = this.start.bind(this);
    this.root = new StateNode(config, {
      _key: this.id,
      _machine: this
    });
    this.root._initialize();
    this.states = this.root.states; // TODO: remove!
    this.events = this.root.events;
    if (!('output' in this.root) && Object.values(this.states).some(state => state.type === 'final' && 'output' in state)) {
      console.warn('Missing `machine.output` declaration (top-level final state with output detected)');
    }
  }

  /**
   * Clones this state machine with the provided implementations
   * and merges the `context` (if provided).
   *
   * @param implementations Options (`actions`, `guards`, `actors`, `delays`, `context`)
   *  to recursively merge with the existing options.
   *
   * @returns A new `StateMachine` instance with the provided implementations.
   */
  provide(implementations) {
    const {
      actions,
      guards,
      actors,
      delays
    } = this.implementations;
    return new StateMachine(this.config, {
      actions: {
        ...actions,
        ...implementations.actions
      },
      guards: {
        ...guards,
        ...implementations.guards
      },
      actors: {
        ...actors,
        ...implementations.actors
      },
      delays: {
        ...delays,
        ...implementations.delays
      }
    });
  }
  resolveState(config) {
    const resolvedStateValue = resolveStateValue(this.root, config.value);
    const nodeSet = getAllStateNodes(getStateNodes(this.root, resolvedStateValue));
    return createMachineSnapshot({
      _nodes: [...nodeSet],
      context: config.context || {},
      children: {},
      status: isInFinalState(nodeSet, this.root) ? 'done' : config.status || 'active',
      output: config.output,
      error: config.error,
      historyValue: config.historyValue
    }, this);
  }

  /**
   * Determines the next snapshot given the current `snapshot` and received `event`.
   * Calculates a full macrostep from all microsteps.
   *
   * @param snapshot The current snapshot
   * @param event The received event
   */
  transition(snapshot, event, actorScope) {
    return macrostep(snapshot, event, actorScope).snapshot;
  }

  /**
   * Determines the next state given the current `state` and `event`.
   * Calculates a microstep.
   *
   * @param state The current state
   * @param event The received event
   */
  microstep(snapshot, event, actorScope) {
    return macrostep(snapshot, event, actorScope).microstates;
  }
  getTransitionData(snapshot, event) {
    return transitionNode(this.root, snapshot.value, snapshot, event) || [];
  }

  /**
   * The initial state _before_ evaluating any microsteps.
   * This "pre-initial" state is provided to initial actions executed in the initial state.
   */
  getPreInitialState(actorScope, initEvent, internalQueue) {
    const {
      context
    } = this.config;
    const preInitial = createMachineSnapshot({
      context: typeof context !== 'function' && context ? context : {},
      _nodes: [this.root],
      children: {},
      status: 'active'
    }, this);
    if (typeof context === 'function') {
      const assignment = ({
        spawn,
        event,
        self
      }) => context({
        spawn,
        input: event.input,
        self
      });
      return resolveActionsAndContext(preInitial, initEvent, actorScope, [assign(assignment)], internalQueue);
    }
    return preInitial;
  }

  /**
   * Returns the initial `State` instance, with reference to `self` as an `ActorRef`.
   */
  getInitialSnapshot(actorScope, input) {
    const initEvent = createInitEvent(input); // TODO: fix;
    const internalQueue = [];
    const preInitialState = this.getPreInitialState(actorScope, initEvent, internalQueue);
    const nextState = microstep([{
      target: [...getInitialStateNodes(this.root)],
      source: this.root,
      reenter: true,
      actions: [],
      eventType: null,
      toJSON: null // TODO: fix
    }], preInitialState, actorScope, initEvent, true, internalQueue);
    const {
      snapshot: macroState
    } = macrostep(nextState, initEvent, actorScope, internalQueue);
    return macroState;
  }
  start(snapshot) {
    Object.values(snapshot.children).forEach(child => {
      if (child.getSnapshot().status === 'active') {
        child.start();
      }
    });
  }
  getStateNodeById(stateId) {
    const fullPath = toStatePath(stateId);
    const relativePath = fullPath.slice(1);
    const resolvedStateId = isStateId(fullPath[0]) ? fullPath[0].slice(STATE_IDENTIFIER.length) : fullPath[0];
    const stateNode = this.idMap.get(resolvedStateId);
    if (!stateNode) {
      throw new Error(`Child state node '#${resolvedStateId}' does not exist on machine '${this.id}'`);
    }
    return getStateNodeByPath(stateNode, relativePath);
  }
  get definition() {
    return this.root.definition;
  }
  toJSON() {
    return this.definition;
  }
  getPersistedSnapshot(snapshot, options) {
    return getPersistedSnapshot(snapshot, options);
  }
  restoreSnapshot(snapshot, _actorScope) {
    const children = {};
    const snapshotChildren = snapshot.children;
    Object.keys(snapshotChildren).forEach(actorId => {
      const actorData = snapshotChildren[actorId];
      const childState = actorData.snapshot;
      const src = actorData.src;
      const logic = typeof src === 'string' ? resolveReferencedActor(this, src) : src;
      if (!logic) {
        return;
      }
      const actorRef = createActor(logic, {
        id: actorId,
        parent: _actorScope.self,
        syncSnapshot: actorData.syncSnapshot,
        snapshot: childState,
        src,
        systemId: actorData.systemId
      });
      children[actorId] = actorRef;
    });
    const restoredSnapshot = createMachineSnapshot({
      ...snapshot,
      children,
      _nodes: Array.from(getAllStateNodes(getStateNodes(this.root, snapshot.value)))
    }, this);
    let seen = new Set();
    function reviveContext(contextPart, children) {
      if (seen.has(contextPart)) {
        return;
      }
      seen.add(contextPart);
      for (let key in contextPart) {
        const value = contextPart[key];
        if (value && typeof value === 'object') {
          if ('xstate$$type' in value && value.xstate$$type === $$ACTOR_TYPE) {
            contextPart[key] = children[value.id];
            continue;
          }
          reviveContext(value, children);
        }
      }
    }
    reviveContext(restoredSnapshot.context, children);
    return restoredSnapshot;
  }
}

const defaultWaitForOptions = {
  timeout: Infinity // much more than 10 seconds
};

/**
 * Subscribes to an actor ref and waits for its emitted value to satisfy
 * a predicate, and then resolves with that value.
 * Will throw if the desired state is not reached after an optional timeout.
 * (defaults to Infinity).
 *
 * @example
 * ```js
 * const state = await waitFor(someService, state => {
 *   return state.hasTag('loaded');
 * });
 *
 * state.hasTag('loaded'); // true
 * ```
 *
 * @param actorRef The actor ref to subscribe to
 * @param predicate Determines if a value matches the condition to wait for
 * @param options
 * @returns A promise that eventually resolves to the emitted value
 * that matches the condition
 */
function waitFor(actorRef, predicate, options) {
  const resolvedOptions = {
    ...defaultWaitForOptions,
    ...options
  };
  return new Promise((res, rej) => {
    let done = false;
    if (resolvedOptions.timeout < 0) {
      console.error('`timeout` passed to `waitFor` is negative and it will reject its internal promise immediately.');
    }
    const handle = resolvedOptions.timeout === Infinity ? undefined : setTimeout(() => {
      sub.unsubscribe();
      rej(new Error(`Timeout of ${resolvedOptions.timeout} ms exceeded`));
    }, resolvedOptions.timeout);
    const dispose = () => {
      clearTimeout(handle);
      done = true;
      sub?.unsubscribe();
    };
    function checkEmitted(emitted) {
      if (predicate(emitted)) {
        dispose();
        res(emitted);
      }
    }
    let sub; // avoid TDZ when disposing synchronously

    // See if the current snapshot already matches the predicate
    checkEmitted(actorRef.getSnapshot());
    if (done) {
      return;
    }
    sub = actorRef.subscribe({
      next: checkEmitted,
      error: err => {
        dispose();
        rej(err);
      },
      complete: () => {
        dispose();
        rej(new Error(`Actor terminated without satisfying predicate`));
      }
    });
    if (done) {
      sub.unsubscribe();
    }
  });
}

// this is not 100% accurate since we can't make parallel regions required in the result
// `TTestValue` doesn't encode this information anyhow for us to be able to do that
// this is fine for most practical use cases anyway though
/**
 * Creates a state machine (statechart) with the given configuration.
 *
 * The state machine represents the pure logic of a state machine actor.
 *
 * @param config The state machine configuration.
 * @param options DEPRECATED: use `setup({ ... })` or `machine.provide({ ... })` to provide machine implementations instead.
 *
 * @example
  ```ts
  import { createMachine } from 'xstate';

  const lightMachine = createMachine({
    id: 'light',
    initial: 'green',
    states: {
      green: {
        on: {
          TIMER: { target: 'yellow' }
        }
      },
      yellow: {
        on: {
          TIMER: { target: 'red' }
        }
      },
      red: {
        on: {
          TIMER: { target: 'green' }
        }
      }
    }
  });

  const lightActor = createActor(lightMachine);
  lightActor.start();

  lightActor.send({ type: 'TIMER' });
  ```
 */
function createMachine(config, implementations) {
  return new StateMachine(config, implementations);
}

/** @internal */
function createInertActorScope(actorLogic) {
  const self = createActor(actorLogic);
  const inertActorScope = {
    self,
    defer: () => {},
    id: '',
    logger: () => {},
    sessionId: '',
    stopChild: () => {},
    system: self.system,
    emit: () => {}
  };
  return inertActorScope;
}
function getInitialSnapshot(actorLogic, ...[input]) {
  const actorScope = createInertActorScope(actorLogic);
  return actorLogic.getInitialSnapshot(actorScope, input);
}

/**
 * Determines the next snapshot for the given `actorLogic` based on
 * the given `snapshot` and `event`.
 *
 * If the `snapshot` is `undefined`, the initial snapshot of the
 * `actorLogic` is used.
 *
 * @example
  ```ts
  import { getNextSnapshot } from 'xstate';
  import { trafficLightMachine } from './trafficLightMachine.ts';

  const nextSnapshot = getNextSnapshot(
    trafficLightMachine, // actor logic
    undefined, // snapshot (or initial state if undefined)
    { type: 'TIMER' }); // event object

  console.log(nextSnapshot.value);
  // => 'yellow'

  const nextSnapshot2 = getNextSnapshot(
    trafficLightMachine, // actor logic
    nextSnapshot, // snapshot
    { type: 'TIMER' }); // event object

  console.log(nextSnapshot2.value);
  // =>'red'
  ```
 */
function getNextSnapshot(actorLogic, snapshot, event) {
  const inertActorScope = createInertActorScope(actorLogic);
  inertActorScope.self._snapshot = snapshot;
  return actorLogic.transition(snapshot, event, inertActorScope);
}

// at the moment we allow extra actors - ones that are not specified by `children`
// this could be reconsidered in the future
function setup({
  schemas,
  actors,
  actions,
  guards,
  delays
}) {
  return {
    createMachine: config => createMachine({
      ...config,
      schemas
    }, {
      actors,
      actions,
      guards,
      delays
    })
  };
}

/**
 * Returns a promise that resolves to the `output` of the actor when it is done.
 *
 * @example
 * ```ts
 * const machine = createMachine({
 *   // ...
 *   output: {
 *     count: 42
 *   }
 * });
 *
 * const actor = createActor(machine);
 *
 * actor.start();
 *
 * const output = await toPromise(actor);
 *
 * console.log(output);
 * // logs { count: 42 }
 * ```
 */
function toPromise(actor) {
  return new Promise((resolve, reject) => {
    actor.subscribe({
      complete: () => {
        resolve(actor.getSnapshot().output);
      },
      error: reject
    });
  });
}

/**
 * Asserts that the given event object is of the specified type or types.
 * Throws an error if the event object is not of the specified types.
  @example

  ```ts
  // ...
  entry: ({ event }) => {
    assertEvent(event, 'doNothing');
    // event is { type: 'doNothing' }
  },
  // ...
  exit: ({ event }) => {
    assertEvent(event, 'greet');
    // event is { type: 'greet'; message: string }

    assertEvent(event, ['greet', 'notify']);
    // event is { type: 'greet'; message: string }
    // or { type: 'notify'; message: string; level: 'info' | 'error' }
  },
  ```
 */
function assertEvent(event, type) {
  const types = toArray(type);
  if (!types.includes(event.type)) {
    const typesText = types.length === 1 ? `type "${types[0]}"` : `one of types "${types.join('", "')}"`;
    throw new Error(`Expected event ${JSON.stringify(event)} to have ${typesText}`);
  }
}

export { SimulatedClock, StateMachine, StateNode, assertEvent, createMachine, getInitialSnapshot, getNextSnapshot, setup, toPromise, waitFor };