livebook/assets/test/lib/delta.test.js

import Delta from "../../js/lib/delta";

describe("Delta", () => {
  describe("compose", () => {
    test("insert with insert", () => {
      const a = new Delta().insert("A");
      const b = new Delta().insert("B");
      const expected = new Delta().insert("B").insert("A");

      expect(a.compose(b)).toEqual(expected);
    });

    test("insert with retain", () => {
      const a = new Delta().insert("A");
      const b = new Delta().retain(1);
      const expected = new Delta().insert("A");

      expect(a.compose(b)).toEqual(expected);
    });

    test("insert with delete", () => {
      const a = new Delta().insert("A");
      const b = new Delta().delete(1);
      const expected = new Delta();

      expect(a.compose(b)).toEqual(expected);
    });

    test("retain with insert", () => {
      const a = new Delta().retain(1);
      const b = new Delta().insert("B");
      const expected = new Delta().insert("B");

      expect(a.compose(b)).toEqual(expected);
    });

    test("retain with retain", () => {
      const a = new Delta().retain(1);
      const b = new Delta().retain(1);
      const expected = new Delta();

      expect(a.compose(b)).toEqual(expected);
    });

    test("retain with delete", () => {
      const a = new Delta().retain(1);
      const b = new Delta().delete(1);
      const expected = new Delta().delete(1);

      expect(a.compose(b)).toEqual(expected);
    });

    test("delete with insert", () => {
      const a = new Delta().delete(1);
      const b = new Delta().insert("B");
      const expected = new Delta().insert("B").delete(1);

      expect(a.compose(b)).toEqual(expected);
    });

    test("delete with retain", () => {
      const a = new Delta().delete(1);
      const b = new Delta().retain(1);
      const expected = new Delta().delete(1);

      expect(a.compose(b)).toEqual(expected);
    });

    test("delete with delete", () => {
      const a = new Delta().delete(1);
      const b = new Delta().delete(1);
      const expected = new Delta().delete(2);

      expect(a.compose(b)).toEqual(expected);
    });

    test("insert in the middle of a text", () => {
      const a = new Delta().insert("Hello");
      const b = new Delta().retain(3).insert("X");
      const expected = new Delta().insert("HelXlo");

      expect(a.compose(b)).toEqual(expected);
    });

    test("insert and delete with different ordering", () => {
      const a = new Delta().insert("Hello");
      const b = new Delta().insert("Hello");

      const insertFirst = new Delta().retain(3).insert("X").delete(1);

      const deleteFirst = new Delta().retain(3).delete(1).insert("X");

      const expected = new Delta().insert("HelXo");

      expect(a.compose(insertFirst)).toEqual(expected);
      expect(b.compose(deleteFirst)).toEqual(expected);
    });

    test("retain then insert with delete entire text", () => {
      const a = new Delta().retain(4).insert("Hello");
      const b = new Delta().delete(9);
      const expected = new Delta().delete(4);

      expect(a.compose(b)).toEqual(expected);
    });

    test("retain more than the length of text", () => {
      const a = new Delta().insert("Hello");
      const b = new Delta().retain(10);
      const expected = new Delta().insert("Hello");

      expect(a.compose(b)).toEqual(expected);
    });
  });

  describe("transform", () => {
    test("insert against insert", () => {
      const a = new Delta().insert("A");
      const b = new Delta().insert("B");
      const bPrimeAssumingAFirst = new Delta().retain(1).insert("B");
      const bPrimeAssumingBFirst = new Delta().insert("B");

      expect(a.transform(b, "left")).toEqual(bPrimeAssumingAFirst);
      expect(a.transform(b, "right")).toEqual(bPrimeAssumingBFirst);
    });

    test("retain against insert", () => {
      const a = new Delta().insert("A");
      // Add insert, so that trailing retain is not trimmed (same in other places)
      const b = new Delta().retain(1).insert("B");
      const bPrime = new Delta().retain(2).insert("B");

      expect(a.transform(b, "right")).toEqual(bPrime);
    });

    test("delete against insert", () => {
      const a = new Delta().insert("A");
      const b = new Delta().delete(1);
      const bPrime = new Delta().retain(1).delete(1);

      expect(a.transform(b, "right")).toEqual(bPrime);
    });

    test("insert against delete", () => {
      const a = new Delta().delete(1);
      const b = new Delta().insert("B");
      const bPrime = new Delta().insert("B");

      expect(a.transform(b, "right")).toEqual(bPrime);
    });

    test("retain against delete", () => {
      const a = new Delta().delete(1);
      const b = new Delta().retain(1).insert("B");
      const bPrime = new Delta().insert("B");

      expect(a.transform(b, "right")).toEqual(bPrime);
    });

    test("delete against delete", () => {
      const a = new Delta().delete(1);
      const b = new Delta().delete(1);
      const bPrime = new Delta();

      expect(a.transform(b, "right")).toEqual(bPrime);
    });

    test("insert against retain", () => {
      const a = new Delta().retain(1).insert("A");
      const b = new Delta().insert("B");
      const bPrime = new Delta().insert("B");

      expect(a.transform(b, "right")).toEqual(bPrime);
    });

    test("retain against retain", () => {
      const a = new Delta().retain(1).insert("A");
      const b = new Delta().retain(1).insert("B");
      const bPrime = new Delta().retain(1).insert("B");

      expect(a.transform(b, "right")).toEqual(bPrime);
    });

    test("delete against retain", () => {
      const a = new Delta().retain(1);
      const b = new Delta().delete(1);
      const bPrime = new Delta().delete(1);

      expect(a.transform(b, "right")).toEqual(bPrime);
    });

    test("multiple edits", () => {
      const a = new Delta().retain(2).insert("aa").delete(5);

      const b = new Delta()
        .retain(1)
        .insert("b")
        .delete(5)
        .retain(1)
        .insert("bb");

      const bPrimeAssumingBFirst = new Delta()
        .retain(1)
        .insert("b")
        .delete(1)
        .retain(2)
        .insert("bb");

      const aPrimeAssumingBFirst = new Delta().retain(2).insert("aa").delete(1);

      expect(a.transform(b, "right")).toEqual(bPrimeAssumingBFirst);
      expect(b.transform(a, "left")).toEqual(aPrimeAssumingBFirst);
    });

    test("conflicting appends", () => {
      const a = new Delta().retain(3).insert("aa");
      const b = new Delta().retain(3).insert("bb");
      const bPrimeAssumingBFirst = new Delta().retain(3).insert("bb");
      const aPrimeAssumingBFirst = new Delta().retain(5).insert("aa");

      expect(a.transform(b, "right")).toEqual(bPrimeAssumingBFirst);
      expect(b.transform(a, "left")).toEqual(aPrimeAssumingBFirst);
    });

    test("prepend and append", () => {
      const a = new Delta().insert("aa");
      const b = new Delta().retain(3).insert("bb");
      const bPrime = new Delta().retain(5).insert("bb");
      const aPrime = new Delta().insert("aa");

      expect(a.transform(b, "right")).toEqual(bPrime);
      expect(b.transform(a, "left")).toEqual(aPrime);
    });

    test("trailing deletes with differing lengths", () => {
      const a = new Delta().retain(2).delete(1);
      const b = new Delta().delete(3);
      const bPrime = new Delta().delete(2);
      const aPrime = new Delta();

      expect(a.transform(b, "right")).toEqual(bPrime);
      expect(b.transform(a, "left")).toEqual(aPrime);
    });

    test("immutability", () => {
      const a = new Delta().insert("A");
      const b = new Delta().insert("B");
      const bPrime = new Delta().retain(1).insert("B");
      expect(a.transform(b, "left")).toEqual(bPrime);

      expect(a).toEqual(new Delta().insert("A"));
      expect(b).toEqual(new Delta().insert("B"));
    });
  });

  describe("applyToString", () => {
    test("prepend", () => {
      const string = "cats";
      const delta = new Delta().insert("fat ");
      const result = delta.applyToString(string);
      expect(result).toEqual("fat cats");
    });

    test("insert in the middle", () => {
      const string = "cats";
      const delta = new Delta().retain(3).insert("'");
      const result = delta.applyToString(string);
      expect(result).toEqual("cat's");
    });

    test("delete", () => {
      const string = "cats";
      const delta = new Delta().retain(1).delete(2);
      const result = delta.applyToString(string);
      expect(result).toEqual("cs");
    });

    test("replace", () => {
      const string = "cats";
      const delta = new Delta().retain(1).delete(2).insert("ar");
      const result = delta.applyToString(string);
      expect(result).toEqual("cars");
    });
  });
});