vscode-cowriting-plugin/test/trackChangesModel.test.ts

import { describe, it, expect } from "vitest";
import { splitBlocks, splitBlocksWithRanges, diffBlocks, renderTrackChanges } from "../src/trackChangesModel";

describe("splitBlocks", () => {
  it("splits prose paragraphs on blank lines, dropping empties", () => {
    const blocks = splitBlocks("# Heading\n\nFirst para.\n\nSecond para.\n");
    expect(blocks.map((b) => b.type)).toEqual(["prose", "prose", "prose"]);
    expect(blocks[0].raw).toBe("# Heading");
    expect(blocks[2].raw).toBe("Second para.");
  });

  it("keeps a fenced code block whole and tags it `code`", () => {
    const text = "Intro.\n\n```ts\nconst a = 1;\n\nconst b = 2;\n```\n\nOutro.\n";
    const blocks = splitBlocks(text);
    expect(blocks.map((b) => b.type)).toEqual(["prose", "code", "prose"]);
    expect(blocks[1].raw).toBe("```ts\nconst a = 1;\n\nconst b = 2;\n```");
  });

  it("tags a mermaid fence `mermaid`", () => {
    const blocks = splitBlocks("```mermaid\nflowchart LR\n  a-->b\n```\n");
    expect(blocks).toHaveLength(1);
    expect(blocks[0].type).toBe("mermaid");
  });

  it("normalizes the key (whitespace-collapsed) for matching", () => {
    const blocks = splitBlocks("Hello    world\n");
    expect(blocks[0].key).toBe("hello world");
  });
});

describe("diffBlocks", () => {
  const kinds = (base: string, cur: string) => diffBlocks(base, cur).map((o) => o.kind);

  it("unchanged doc → all unchanged", () => {
    const doc = "Alpha.\n\nBravo.\n";
    expect(kinds(doc, doc)).toEqual(["unchanged", "unchanged"]);
  });

  it("a pure addition → an added op", () => {
    const ops = diffBlocks("Alpha.\n", "Alpha.\n\nBravo.\n");
    expect(ops.map((o) => o.kind)).toEqual(["unchanged", "added"]);
  });

  it("a pure deletion → a removed op", () => {
    const ops = diffBlocks("Alpha.\n\nBravo.\n", "Alpha.\n");
    expect(ops.map((o) => o.kind)).toEqual(["unchanged", "removed"]);
  });

  it("a prose modification → a non-atomic changed op", () => {
    const ops = diffBlocks("The quick fox.\n", "The slow fox.\n");
    expect(ops).toHaveLength(1);
    expect(ops[0].kind).toBe("changed");
    expect(ops[0].kind === "changed" && ops[0].atomic).toBe(false);
  });

  it("a code-fence change → an ATOMIC changed op (INV-23)", () => {
    const base = "```ts\nconst a = 1;\n```\n";
    const cur = "```ts\nconst a = 2;\n```\n";
    const ops = diffBlocks(base, cur);
    expect(ops).toHaveLength(1);
    expect(ops[0].kind).toBe("changed");
    expect(ops[0].kind === "changed" && ops[0].atomic).toBe(true);
  });

  it("a mermaid-fence change → an ATOMIC changed op", () => {
    const base = "```mermaid\nflowchart LR\n a-->b\n```\n";
    const cur = "```mermaid\nflowchart LR\n a-->c\n```\n";
    const ops = diffBlocks(base, cur);
    expect(ops[0].kind).toBe("changed");
    expect(ops[0].kind === "changed" && ops[0].atomic).toBe(true);
  });

  it("a reorder → keeps a matched block unchanged", () => {
    const ops = diffBlocks("One.\n\nTwo.\n", "Two.\n\nOne.\n");
    const k = ops.map((o) => o.kind);
    expect(k).toContain("unchanged");
  });
});

describe("renderTrackChanges", () => {
  it("wraps each block in a cw-blk div with its kind class", () => {
    const html = renderTrackChanges("Alpha.\n", "Alpha.\n\nBravo.\n");
    expect(html).toContain('class="cw-blk cw-unchanged"');
    expect(html).toContain('class="cw-blk cw-added"');
  });

  it("emits inline <ins>/<del> for a prose modification", () => {
    const html = renderTrackChanges("The quick fox.\n", "The slow fox.\n");
    expect(html).toContain("<ins>");
    expect(html).toContain("<del>");
    expect(html).toContain("cw-changed");
  });

  it("renders a changed CODE fence atomically: cw-changed, no inline ins/del", () => {
    const html = renderTrackChanges("```ts\nconst a = 1;\n```\n", "```ts\nconst a = 2;\n```\n");
    expect(html).toContain("cw-changed");
    expect(html).not.toContain("<ins>");
    expect(html).not.toContain("<del>");
    expect(html).toContain("cw-badge");
  });

  it('emits <pre class="mermaid"> for a mermaid fence + a changed badge', () => {
    const html = renderTrackChanges(
      "```mermaid\nflowchart LR\n a-->b\n```\n",
      "```mermaid\nflowchart LR\n a-->c\n```\n",
    );
    expect(html).toContain('<pre class="mermaid">');
    expect(html).toContain("a--&gt;c"); // current source, escaped
    expect(html).toContain("cw-badge");
  });

  it("unchanged doc renders with no marks", () => {
    const html = renderTrackChanges("Alpha.\n", "Alpha.\n");
    expect(html).not.toContain("cw-added");
    expect(html).not.toContain("cw-removed");
    expect(html).not.toContain("cw-changed");
  });

  it("is deterministic (same inputs → identical HTML) (INV-22)", () => {
    const a = renderTrackChanges("X.\n\nY.\n", "X.\n\nZ.\n");
    const b = renderTrackChanges("X.\n\nY.\n", "X.\n\nZ.\n");
    expect(a).toBe(b);
  });
});

describe("error chip (PUC-6)", () => {
  it("a block whose render throws becomes an error chip; the rest still renders", () => {
    const throwing = (src: string) => {
      if (src.includes("BOOM")) throw new Error("kaboom");
      return `<p>${src}</p>`;
    };
    const html = renderTrackChanges("Good one.\n\nBOOM here.\n", "Good one.\n\nBOOM here.\n", {
      render: throwing,
    });
    expect(html).toContain("cw-error");
    expect(html).toContain("kaboom");
    expect(html).toContain("<p>Good one.</p>"); // the healthy block still rendered
  });
});

describe("splitBlocksWithRanges — block offsets align with the source string", () => {
  it("each block's [start,end) slices back to its raw from the source", () => {
    const text = "# Title\n\nA prose paragraph.\n\n```js\ncode()\n```\n";
    const blocks = splitBlocksWithRanges(text);
    expect(blocks.map((b) => b.type)).toEqual(["prose", "prose", "code"]);
    for (const b of blocks) {
      expect(text.slice(b.start, b.end)).toBe(b.raw);
    }
    expect(blocks[1].raw).toBe("A prose paragraph.");
  });

  it("marks a mermaid fence and preserves its source offsets", () => {
    const text = "intro\n\n```mermaid\ngraph TD; A-->B;\n```\n";
    const blocks = splitBlocksWithRanges(text);
    expect(blocks[1].type).toBe("mermaid");
    expect(text.slice(blocks[1].start, blocks[1].end)).toBe(blocks[1].raw);
  });
});