fastest-levenshtein/test.ts

const { closest, distance } = require("./mod.js");

const levenshtein = (a, b) => {
  if (a.length === 0) {
    return b.length;
  }
  if (b.length === 0) {
    return a.length;
  }

  if (a.length > b.length) {
    const tmp = a;
    a = b;
    b = tmp;
  }

  const row = [];
  for (let i = 0; i <= a.length; i++) {
    row[i] = i;
  }

  for (let i = 1; i <= b.length; i++) {
    let prev = i;
    for (let j = 1; j <= a.length; j++) {
      let val = 0;
      if (b.charAt(i - 1) === a.charAt(j - 1)) {
        val = row[j - 1];
      } else {
        val = Math.min(row[j - 1] + 1, prev + 1, row[j] + 1);
      }
      row[j - 1] = prev;
      prev = val;
    }
    row[a.length] = prev;
  }

  return row[a.length];
};

const makeid = (length) => {
  let result = "";
  const characters =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
  const charactersLength = characters.length;
  for (let i = 0; i < length; i++) {
    result += characters.charAt(Math.floor(Math.random() * charactersLength));
  }
  return result;
};

test("test compare", () => {
  for (let i = 0; i < 1000; i++) {
    const rnd_num1 = (Math.random() * 1000) | 0;
    const rnd_num2 = (Math.random() * 1000) | 0;
    const rnd_string1 = makeid(rnd_num1);
    const rnd_string2 = makeid(rnd_num2);
    const actual = distance(rnd_string1, rnd_string2);
    const expected = levenshtein(rnd_string1, rnd_string2);
    expect(actual).toBe(expected);
  }
});

test("test find", () => {
  const actual = closest("fast", ["slow", "faster", "fastest"]);
  const expected = "faster";
  expect(actual).toBe(expected);
});