The city provides its citizens with a Walk Generating App on their phones -- every time you press the button it sends you an array of one-letter strings representing directions to walk (eg. ['n', 's', 'w', 'e']). You always walk only a single block for each letter (direction) and you know it takes you one minute to traverse one city block, so cr…

walkInCartesia.js

/**
 * production code
 */

const backFromWalkInTime = (steps) => {
  const stepsUp = steps.filter((step) => step === "n").length;
  const stepsDown = steps.filter((step) => step === "s").length;
  const stepsLeft = steps.filter((step) => step === "e").length;
  const stepsRight = steps.filter((step) => step === "w").length;

  return (
    steps.length === 10 && stepsUp === stepsDown && stepsLeft === stepsRight
  );
};

/**
 * unit tests
 */

mocha.setup("bdd");
const assert = chai.assert;

describe("given an array containing coordinates, checking if I will be back from walk in time", () => {
  describe("when the sequence of steps is balanced", () => {
    it("should return true", function () {
      assert.equal(
        backFromWalkInTime(["n", "e", "w", "s", "n", "w", "w", "e", "e", "s"]),
        true
      );
    });
  });

  describe("when the sequence of steps is NOT balanced", () => {
    it("should return false", function () {
      assert.equal(
        backFromWalkInTime(["s", "e", "w", "s", "n", "w", "w", "e", "e", "s"]),
        false
      );
    });
  });

  describe("when it has less than 10 steps", () => {
    it("should return false", function () {
      assert.equal(backFromWalkInTime(["n", "e", "w"]), false);
    });
  });

  describe("when it is empty", () => {
    it("should return false", function () {
      assert.equal(backFromWalkInTime([]), false);
    });
  });
});

mocha.run();