element-web/test/unit-tests/editor/diff-test.ts

/*
Copyright 2024 New Vector Ltd.
Copyright 2019 The Matrix.org Foundation C.I.C.

SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only
Please see LICENSE files in the repository root for full details.
*/

import { diffDeletion, diffAtCaret } from "../../src/editor/diff";

describe("editor/diff", function () {
    describe("diffDeletion", function () {
        describe("with a single character removed", function () {
            it("at start of string", function () {
                const diff = diffDeletion("hello", "ello");
                expect(diff.at).toBe(0);
                expect(diff.removed).toBe("h");
            });
            it("in middle of string", function () {
                const diff = diffDeletion("hello", "hllo");
                expect(diff.at).toBe(1);
                expect(diff.removed).toBe("e");
            });
            it("in middle of string with duplicate character", function () {
                const diff = diffDeletion("hello", "helo");
                expect(diff.at).toBe(3);
                expect(diff.removed).toBe("l");
            });
            it("at end of string", function () {
                const diff = diffDeletion("hello", "hell");
                expect(diff.at).toBe(4);
                expect(diff.removed).toBe("o");
            });
        });
        describe("with a multiple removed", function () {
            it("at start of string", function () {
                const diff = diffDeletion("hello", "llo");
                expect(diff.at).toBe(0);
                expect(diff.removed).toBe("he");
            });
            it("removing whole string", function () {
                const diff = diffDeletion("hello", "");
                expect(diff.at).toBe(0);
                expect(diff.removed).toBe("hello");
            });
            it("in middle of string", function () {
                const diff = diffDeletion("hello", "hlo");
                expect(diff.at).toBe(1);
                expect(diff.removed).toBe("el");
            });
            it("in middle of string with duplicate character", function () {
                const diff = diffDeletion("hello", "heo");
                expect(diff.at).toBe(2);
                expect(diff.removed).toBe("ll");
            });
            it("at end of string", function () {
                const diff = diffDeletion("hello", "hel");
                expect(diff.at).toBe(3);
                expect(diff.removed).toBe("lo");
            });
        });
    });
    describe("diffAtCaret", function () {
        it("insert at start", function () {
            const diff = diffAtCaret("world", "hello world", 6);
            expect(diff.at).toBe(0);
            expect(diff.added).toBe("hello ");
            expect(diff.removed).toBeFalsy();
        });
        it("insert at end", function () {
            const diff = diffAtCaret("hello", "hello world", 11);
            expect(diff.at).toBe(5);
            expect(diff.added).toBe(" world");
            expect(diff.removed).toBeFalsy();
        });
        it("insert in middle", function () {
            const diff = diffAtCaret("hello world", "hello cruel world", 12);
            expect(diff.at).toBe(6);
            expect(diff.added).toBe("cruel ");
            expect(diff.removed).toBeFalsy();
        });
        it("replace at start", function () {
            const diff = diffAtCaret("morning, world!", "afternoon, world!", 9);
            expect(diff.at).toBe(0);
            expect(diff.removed).toBe("morning");
            expect(diff.added).toBe("afternoon");
        });
        it("replace at end", function () {
            const diff = diffAtCaret("morning, world!", "morning, mars?", 14);
            expect(diff.at).toBe(9);
            expect(diff.removed).toBe("world!");
            expect(diff.added).toBe("mars?");
        });
        it("replace in middle", function () {
            const diff = diffAtCaret("morning, blue planet", "morning, red planet", 12);
            expect(diff.at).toBe(9);
            expect(diff.removed).toBe("blue");
            expect(diff.added).toBe("red");
        });
        it("remove at start of string", function () {
            const diff = diffAtCaret("hello", "ello", 0);
            expect(diff.at).toBe(0);
            expect(diff.removed).toBe("h");
            expect(diff.added).toBeFalsy();
        });
        it("removing whole string", function () {
            const diff = diffAtCaret("hello", "", 0);
            expect(diff.at).toBe(0);
            expect(diff.removed).toBe("hello");
            expect(diff.added).toBeFalsy();
        });
        it("remove in middle of string", function () {
            const diff = diffAtCaret("hello", "hllo", 1);
            expect(diff.at).toBe(1);
            expect(diff.removed).toBe("e");
            expect(diff.added).toBeFalsy();
        });
        it("forwards remove in middle of string", function () {
            const diff = diffAtCaret("hello", "hell", 4);
            expect(diff.at).toBe(4);
            expect(diff.removed).toBe("o");
            expect(diff.added).toBeFalsy();
        });
        it("forwards remove in middle of string with duplicate character", function () {
            const diff = diffAtCaret("hello", "helo", 3);
            expect(diff.at).toBe(3);
            expect(diff.removed).toBe("l");
            expect(diff.added).toBeFalsy();
        });
        it("remove at end of string", function () {
            const diff = diffAtCaret("hello", "hell", 4);
            expect(diff.at).toBe(4);
            expect(diff.removed).toBe("o");
            expect(diff.added).toBeFalsy();
        });
    });
});