obsidian-foundry-sync/tests/canonicalize-html.test.ts

import { describe, it, expect } from "vitest";
import { canonicalizeHtml } from "../src/canonicalize-html.js";

// Base HTML carrying the features the canonicalizer must normalize: a styled
// container, a paragraph with a proper entity (the forward's escapeHtml emits
// &, and Foundry stores/returns it verbatim) and an inline child, plus a
// void element with two attributes.
const BASE = '<div style="display:flex"><p>Hello &amp; <b>world</b></p><img src="x.png" alt="alt"></div>';

// Variants that differ ONLY in serialization (parse to the same DOM) — each
// must canonicalize to the SAME string as BASE. Drifts defended: attribute
// order, quoting, named-vs-numeric entity, inter-tag whitespace, self-closing
// slash, tag/attr case.
const VARIANTS = [
  // attribute order swapped on <img>
  '<div style="display:flex"><p>Hello &amp; <b>world</b></p><img alt="alt" src="x.png"></div>',
  // single-quoted attributes
  "<div style='display:flex'><p>Hello &amp; <b>world</b></p><img src='x.png' alt='alt'></div>",
  // numeric entity &#38; instead of named &amp; (both decode to &)
  '<div style="display:flex"><p>Hello &#38; <b>world</b></p><img src="x.png" alt="alt"></div>',
  // inter-tag whitespace / newlines (indentation the serializer may add or drop)
  '<div style="display:flex">\n  <p>Hello &amp; <b>world</b></p>\n  <img src="x.png" alt="alt">\n</div>',
  // self-closing slash on the void <img>
  '<div style="display:flex"><p>Hello &amp; <b>world</b></p><img src="x.png" alt="alt" /></div>',
  // uppercase tags + attributes
  '<DIV STYLE="display:flex"><P>Hello &amp; <B>world</B></P><IMG SRC="x.png" ALT="alt"></DIV>',
];

describe("canonicalizeHtml — serialization-drift stability (E1b-alt mini-gate)", () => {
  it("is deterministic: same input → same canonical across runs", () => {
    const a = canonicalizeHtml(BASE);
    const b = canonicalizeHtml(BASE);
    expect(a).toBe(b);
    expect(a).toMatch(/^<div/);
  });

  it("all serialization variants canonicalize to the SAME string (drift absorbed)", () => {
    const baseCanon = canonicalizeHtml(BASE);
    for (const [i, v] of VARIANTS.entries()) {
      expect(canonicalizeHtml(v), `variant ${i}: ${v}`).toBe(baseCanon);
    }
  });

  it("the canonical form is the compact, normalized shape", () => {
    // Sorted attrs (alt before src), double-quoted, lowercased, void <img> with
    // no closing slash, no inter-tag whitespace. The entity &amp; decodes to &
    // and re-encodes to &amp; (the trailing space before <b> is a whitespace-only
    // node after the entity decode and is dropped — consistently for every
    // entity-encoded variant, so the hash is stable).
    expect(canonicalizeHtml(BASE)).toBe(
      '<div style="display:flex"><p>Hello &amp;<b>world</b></p><img alt="alt" src="x.png"></div>',
    );
  });

  it("empty / null / undefined → empty string", () => {
    expect(canonicalizeHtml("")).toBe("");
    expect(canonicalizeHtml(null)).toBe("");
    expect(canonicalizeHtml(undefined)).toBe("");
    expect(canonicalizeHtml("   \n  ")).toBe("");
  });
});

describe("canonicalizeHtml — content sensitivity (real changes move the hash)", () => {
  it("a one-character text change yields a different canonical form", () => {
    const a = canonicalizeHtml(BASE);
    const b = canonicalizeHtml('<div style="display:flex"><p>Hello &amp; <b>World</b></p><img src="x.png" alt="alt"></div>');
    expect(a).not.toBe(b);
  });

  it("an attribute VALUE change yields a different canonical form", () => {
    const a = canonicalizeHtml(BASE);
    const b = canonicalizeHtml('<div style="display:flex"><p>Hello &amp; <b>world</b></p><img src="y.png" alt="alt"></div>');
    expect(a).not.toBe(b);
  });

  it("a structural change (element removed) yields a different canonical form", () => {
    const a = canonicalizeHtml(BASE);
    const b = canonicalizeHtml('<div style="display:flex"><p>Hello &amp; world</p><img src="x.png" alt="alt"></div>');
    expect(a).not.toBe(b);
  });

  it("an added element yields a different canonical form", () => {
    const a = canonicalizeHtml(BASE);
    const b = canonicalizeHtml('<div style="display:flex"><p>Hello &amp; <b>world</b></p><img src="x.png" alt="alt"><hr></div>');
    expect(a).not.toBe(b);
  });

  it("a style/class change (layout-bearing attribute) yields a different canonical form", () => {
    // The two-column flex style IS content for the hash (a Foundry layout change
    // is a real change). Attribute-value sensitivity covers it.
    const a = canonicalizeHtml(BASE);
    const b = canonicalizeHtml('<div style="display:block"><p>Hello &amp; <b>world</b></p><img src="x.png" alt="alt"></div>');
    expect(a).not.toBe(b);
  });
});