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