293 lines
12 KiB
JavaScript
293 lines
12 KiB
JavaScript
import { machine, transition } from '~/lib/utils/finite_state_machine';
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describe('Finite State Machine', () => {
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const STATE_IDLE = 'idle';
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const STATE_LOADING = 'loading';
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const STATE_ERRORED = 'errored';
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const TRANSITION_START_LOAD = 'START_LOAD';
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const TRANSITION_LOAD_ERROR = 'LOAD_ERROR';
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const TRANSITION_LOAD_SUCCESS = 'LOAD_SUCCESS';
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const TRANSITION_ACKNOWLEDGE_ERROR = 'ACKNOWLEDGE_ERROR';
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const definition = {
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initial: STATE_IDLE,
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states: {
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[STATE_IDLE]: {
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on: {
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[TRANSITION_START_LOAD]: STATE_LOADING,
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},
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},
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[STATE_LOADING]: {
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on: {
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[TRANSITION_LOAD_ERROR]: STATE_ERRORED,
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[TRANSITION_LOAD_SUCCESS]: STATE_IDLE,
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},
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},
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[STATE_ERRORED]: {
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on: {
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[TRANSITION_ACKNOWLEDGE_ERROR]: STATE_IDLE,
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[TRANSITION_START_LOAD]: STATE_LOADING,
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},
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},
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},
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};
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describe('machine', () => {
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const STATE_IMPOSSIBLE = 'impossible';
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const badDefinition = {
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init: definition.initial,
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badKeyShouldBeStates: definition.states,
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};
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const unstartableDefinition = {
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initial: STATE_IMPOSSIBLE,
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states: definition.states,
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};
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let liveMachine;
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beforeEach(() => {
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liveMachine = machine(definition);
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});
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it('throws an error if the machine definition is invalid', () => {
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expect(() => machine(badDefinition)).toThrowError(
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'A state machine must have an initial state (`.initial`) and a dictionary of possible states (`.states`)',
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);
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});
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it('throws an error if the initial state is invalid', () => {
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expect(() => machine(unstartableDefinition)).toThrowError(
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`Cannot initialize the state machine to state '${STATE_IMPOSSIBLE}'. Is that one of the machine's defined states?`,
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);
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});
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it.each`
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partOfMachine | equals | description | eqDescription
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${'keys'} | ${['is', 'send', 'value', 'states']} | ${'keys'} | ${'the correct array'}
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${'is'} | ${expect.any(Function)} | ${'`is` property'} | ${'a function'}
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${'send'} | ${expect.any(Function)} | ${'`send` property'} | ${'a function'}
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${'value'} | ${definition.initial} | ${'`value` property'} | ${'the same as the `initial` value of the machine definition'}
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${'states'} | ${definition.states} | ${'`states` property'} | ${'the same as the `states` value of the machine definition'}
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`("The machine's $description should be $eqDescription", ({ partOfMachine, equals }) => {
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const test = partOfMachine === 'keys' ? Object.keys(liveMachine) : liveMachine[partOfMachine];
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expect(test).toEqual(equals);
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});
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it.each`
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initialState | transitionEvent | expectedState
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${definition.initial} | ${TRANSITION_START_LOAD} | ${STATE_LOADING}
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${STATE_LOADING} | ${TRANSITION_LOAD_ERROR} | ${STATE_ERRORED}
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${STATE_ERRORED} | ${TRANSITION_ACKNOWLEDGE_ERROR} | ${STATE_IDLE}
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${STATE_IDLE} | ${TRANSITION_START_LOAD} | ${STATE_LOADING}
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${STATE_LOADING} | ${TRANSITION_LOAD_SUCCESS} | ${STATE_IDLE}
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`(
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'properly steps from $initialState to $expectedState when the event "$transitionEvent" is sent',
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({ initialState, transitionEvent, expectedState }) => {
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liveMachine.value = initialState;
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liveMachine.send(transitionEvent);
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expect(liveMachine.is(expectedState)).toBe(true);
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expect(liveMachine.value).toBe(expectedState);
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},
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);
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it.each`
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initialState | transitionEvent
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${STATE_IDLE} | ${TRANSITION_ACKNOWLEDGE_ERROR}
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${STATE_IDLE} | ${TRANSITION_LOAD_SUCCESS}
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${STATE_IDLE} | ${TRANSITION_LOAD_ERROR}
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${STATE_IDLE} | ${'RANDOM_FOO'}
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${STATE_LOADING} | ${TRANSITION_START_LOAD}
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${STATE_LOADING} | ${TRANSITION_ACKNOWLEDGE_ERROR}
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${STATE_LOADING} | ${'RANDOM_FOO'}
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${STATE_ERRORED} | ${TRANSITION_LOAD_ERROR}
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${STATE_ERRORED} | ${TRANSITION_LOAD_SUCCESS}
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${STATE_ERRORED} | ${'RANDOM_FOO'}
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`(
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`does not perform any transition if the machine can't move from "$initialState" using the "$transitionEvent" event`,
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({ initialState, transitionEvent }) => {
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liveMachine.value = initialState;
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liveMachine.send(transitionEvent);
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expect(liveMachine.is(initialState)).toBe(true);
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expect(liveMachine.value).toBe(initialState);
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},
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);
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describe('send', () => {
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it.each`
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startState | transitionEvent | result
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${STATE_IDLE} | ${TRANSITION_START_LOAD} | ${STATE_LOADING}
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${STATE_LOADING} | ${TRANSITION_LOAD_SUCCESS} | ${STATE_IDLE}
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${STATE_LOADING} | ${TRANSITION_LOAD_ERROR} | ${STATE_ERRORED}
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${STATE_ERRORED} | ${TRANSITION_ACKNOWLEDGE_ERROR} | ${STATE_IDLE}
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${STATE_ERRORED} | ${TRANSITION_START_LOAD} | ${STATE_LOADING}
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`(
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'successfully transitions to $result from $startState when the transition $transitionEvent is received',
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({ startState, transitionEvent, result }) => {
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liveMachine.value = startState;
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expect(liveMachine.send(transitionEvent)).toEqual(result);
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},
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);
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it.each`
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startState | transitionEvent
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${STATE_IDLE} | ${TRANSITION_ACKNOWLEDGE_ERROR}
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${STATE_IDLE} | ${TRANSITION_LOAD_SUCCESS}
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${STATE_IDLE} | ${TRANSITION_LOAD_ERROR}
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${STATE_IDLE} | ${'RANDOM_FOO'}
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${STATE_LOADING} | ${TRANSITION_START_LOAD}
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${STATE_LOADING} | ${TRANSITION_ACKNOWLEDGE_ERROR}
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${STATE_LOADING} | ${'RANDOM_FOO'}
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${STATE_ERRORED} | ${TRANSITION_LOAD_ERROR}
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${STATE_ERRORED} | ${TRANSITION_LOAD_SUCCESS}
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${STATE_ERRORED} | ${'RANDOM_FOO'}
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`(
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'remains as $startState if an undefined transition ($transitionEvent) is received',
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({ startState, transitionEvent }) => {
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liveMachine.value = startState;
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expect(liveMachine.send(transitionEvent)).toEqual(startState);
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},
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);
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describe('detached', () => {
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it.each`
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startState | transitionEvent | result
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${STATE_IDLE} | ${TRANSITION_START_LOAD} | ${STATE_LOADING}
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${STATE_LOADING} | ${TRANSITION_LOAD_SUCCESS} | ${STATE_IDLE}
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${STATE_LOADING} | ${TRANSITION_LOAD_ERROR} | ${STATE_ERRORED}
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${STATE_ERRORED} | ${TRANSITION_ACKNOWLEDGE_ERROR} | ${STATE_IDLE}
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${STATE_ERRORED} | ${TRANSITION_START_LOAD} | ${STATE_LOADING}
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`(
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'successfully transitions to $result from $startState when the transition $transitionEvent is received outside the context of the machine',
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({ startState, transitionEvent, result }) => {
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const liveSend = machine({
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...definition,
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initial: startState,
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}).send;
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expect(liveSend(transitionEvent)).toEqual(result);
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},
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);
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it.each`
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startState | transitionEvent
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${STATE_IDLE} | ${TRANSITION_ACKNOWLEDGE_ERROR}
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${STATE_IDLE} | ${TRANSITION_LOAD_SUCCESS}
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${STATE_IDLE} | ${TRANSITION_LOAD_ERROR}
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${STATE_IDLE} | ${'RANDOM_FOO'}
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${STATE_LOADING} | ${TRANSITION_START_LOAD}
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${STATE_LOADING} | ${TRANSITION_ACKNOWLEDGE_ERROR}
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${STATE_LOADING} | ${'RANDOM_FOO'}
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${STATE_ERRORED} | ${TRANSITION_LOAD_ERROR}
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${STATE_ERRORED} | ${TRANSITION_LOAD_SUCCESS}
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${STATE_ERRORED} | ${'RANDOM_FOO'}
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`(
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'remains as $startState if an undefined transition ($transitionEvent) is received',
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({ startState, transitionEvent }) => {
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const liveSend = machine({
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...definition,
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initial: startState,
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}).send;
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expect(liveSend(transitionEvent)).toEqual(startState);
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},
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);
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});
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});
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describe('is', () => {
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it.each`
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bool | test | actual
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${true} | ${STATE_IDLE} | ${STATE_IDLE}
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${false} | ${STATE_LOADING} | ${STATE_IDLE}
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${false} | ${STATE_ERRORED} | ${STATE_IDLE}
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${true} | ${STATE_LOADING} | ${STATE_LOADING}
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${false} | ${STATE_IDLE} | ${STATE_LOADING}
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${false} | ${STATE_ERRORED} | ${STATE_LOADING}
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${true} | ${STATE_ERRORED} | ${STATE_ERRORED}
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${false} | ${STATE_IDLE} | ${STATE_ERRORED}
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${false} | ${STATE_LOADING} | ${STATE_ERRORED}
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`(
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'returns "$bool" for "$test" when the current state is "$actual"',
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({ bool, test, actual }) => {
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liveMachine = machine({
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...definition,
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initial: actual,
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});
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expect(liveMachine.is(test)).toEqual(bool);
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},
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);
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describe('detached', () => {
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it.each`
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bool | test | actual
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${true} | ${STATE_IDLE} | ${STATE_IDLE}
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${false} | ${STATE_LOADING} | ${STATE_IDLE}
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${false} | ${STATE_ERRORED} | ${STATE_IDLE}
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${true} | ${STATE_LOADING} | ${STATE_LOADING}
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${false} | ${STATE_IDLE} | ${STATE_LOADING}
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${false} | ${STATE_ERRORED} | ${STATE_LOADING}
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${true} | ${STATE_ERRORED} | ${STATE_ERRORED}
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${false} | ${STATE_IDLE} | ${STATE_ERRORED}
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${false} | ${STATE_LOADING} | ${STATE_ERRORED}
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`(
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'returns "$bool" for "$test" when the current state is "$actual"',
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({ bool, test, actual }) => {
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const liveIs = machine({
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...definition,
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initial: actual,
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}).is;
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expect(liveIs(test)).toEqual(bool);
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},
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);
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});
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});
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});
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describe('transition', () => {
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it.each`
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startState | transitionEvent | result
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${STATE_IDLE} | ${TRANSITION_START_LOAD} | ${STATE_LOADING}
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${STATE_LOADING} | ${TRANSITION_LOAD_SUCCESS} | ${STATE_IDLE}
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${STATE_LOADING} | ${TRANSITION_LOAD_ERROR} | ${STATE_ERRORED}
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${STATE_ERRORED} | ${TRANSITION_ACKNOWLEDGE_ERROR} | ${STATE_IDLE}
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${STATE_ERRORED} | ${TRANSITION_START_LOAD} | ${STATE_LOADING}
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`(
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'successfully transitions to $result from $startState when the transition $transitionEvent is received',
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({ startState, transitionEvent, result }) => {
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expect(transition(definition, startState, transitionEvent)).toEqual(result);
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},
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);
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it.each`
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startState | transitionEvent
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${STATE_IDLE} | ${TRANSITION_ACKNOWLEDGE_ERROR}
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${STATE_IDLE} | ${TRANSITION_LOAD_SUCCESS}
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${STATE_IDLE} | ${TRANSITION_LOAD_ERROR}
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${STATE_IDLE} | ${'RANDOM_FOO'}
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${STATE_LOADING} | ${TRANSITION_START_LOAD}
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${STATE_LOADING} | ${TRANSITION_ACKNOWLEDGE_ERROR}
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${STATE_LOADING} | ${'RANDOM_FOO'}
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${STATE_ERRORED} | ${TRANSITION_LOAD_ERROR}
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${STATE_ERRORED} | ${TRANSITION_LOAD_SUCCESS}
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${STATE_ERRORED} | ${'RANDOM_FOO'}
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`(
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'remains as $startState if an undefined transition ($transitionEvent) is received',
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({ startState, transitionEvent }) => {
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expect(transition(definition, startState, transitionEvent)).toEqual(startState);
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},
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);
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it('remains as the provided starting state if it is an unrecognized state', () => {
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expect(transition(definition, 'RANDOM_FOO', TRANSITION_START_LOAD)).toEqual('RANDOM_FOO');
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});
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});
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});
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