finitestate/__tests__/counter.test.js

1. All actions are functions which have a $$displayName property. 2. All states are strings 3. Json representation for SSR

import FSM from "../lib";

class Counter extends FSM {
  constructor({ startValue, startState }) {
    super({
      startState,
      startValue,
      transitions: ["increment", "finish", "reset"],
      states: ["start", "end", "running"],
      transitionMap: {
        start: {
          increment: "running",
          finish: "end"
        },
        running: {
          increment: "running",
          finish: "end"
        },
        end: {
          reset: "start"
        }
      }
    });
  }
  increment() {
    return value => value + 1;
  }
  reset() {}
  finish() {}
  shouldTransitionOccur(_, { value }) {
    if (value >= 7) {
      return false;
    }
    return true;
  }
}

let counter;

describe("CounterExample", () => {
  beforeEach(() => {
    counter = new Counter({
      startState: "start",
      startValue: 5
    });
  });

  test("Inherited FSM is a class", () => {
    expect(typeof Counter).toEqual("function");
  });

  test("Inherited FSM instance is an FSM", () => {
    expect(counter).toBeInstanceOf(FSM);
    expect(counter).toBeInstanceOf(Counter);
  });

  test("Inherited FSM interface", () => {
    expect(typeof counter.actions).toBe("object");
    expect(counter.value).toBe(5);
    expect(counter.state).toBe("start");
  });

  test("Inherited FSM transitions from start to running correctly", () => {
    expect(counter.value).toBe(5);
    expect(counter.state).toBe("start");
    counter.actions.increment();
    expect(counter.value).toBe(6);
    expect(counter.state).toBe("running");
  });

  test("Inherited FSM can inform which transitions are valid", () => {
    expect(counter.value).toBe(5);
    expect(counter.state).toBe("start");
    expect(counter.isTransitionValid("finish")).toBe(true);
    expect(counter.isTransitionValid("reset")).toBe(false);
    counter.actions.increment();
    expect(counter.value).toBe(6);
    expect(counter.state).toBe("running");
    expect(counter.isTransitionValid("finish")).toBe(true);
    expect(counter.isTransitionValid("reset")).toBe(false);
    counter.actions.finish();
    expect(counter.value).toBe(6);
    expect(counter.state).toBe("end");
    expect(counter.isTransitionValid("finish")).toBe(false);
    expect(counter.isTransitionValid("reset")).toBe(true);
  });
});