diff-tools/tests/core/directory-merge.test.ts

import { describe, expect, it } from "vitest";
import {
  compareDirectoryManifests,
  createDirectoryManifest,
  parseDirectoryManifest,
  serializeDirectoryManifest,
} from "../../src/core/directory-manifest";
import { mergeThreeWay } from "../../src/core/merge";

function file(path: string, value: string): File {
  const item = new File([value], path.split("/").at(-1)!, {
    lastModified: Date.UTC(2026, 0, 1),
  });
  Object.defineProperty(item, "webkitRelativePath", {
    value: `chosen-root/${path}`,
  });
  return item;
}

describe("directory manifests", () => {
  it("hashes bounded files deterministically and strips the selected root", async () => {
    const first = await createDirectoryManifest([
      file("z.txt", "last"),
      file("nested/a.txt", "first"),
    ]);
    const second = await createDirectoryManifest([
      file("nested/a.txt", "first"),
      file("z.txt", "last"),
    ]);
    expect(first.entries.map((entry) => entry.path)).toEqual([
      "nested/a.txt",
      "z.txt",
    ]);
    expect(first.entries).toEqual(second.entries);
    expect(parseDirectoryManifest(serializeDirectoryManifest(first))).toEqual(
      first,
    );
  });

  it("compares content digests rather than timestamps", async () => {
    const left = await createDirectoryManifest([
      file("same.txt", "same"),
      file("changed.txt", "before"),
      file("removed.txt", "gone"),
    ]);
    const right = await createDirectoryManifest([
      file("same.txt", "same"),
      file("changed.txt", "after"),
      file("added.txt", "new"),
    ]);
    expect(
      compareDirectoryManifests(left, right).map(({ path, status }) => ({
        path,
        status,
      })),
    ).toEqual([
      { path: "added.txt", status: "added" },
      { path: "changed.txt", status: "modified" },
      { path: "removed.txt", status: "removed" },
      { path: "same.txt", status: "same" },
    ]);
  });

  it("rejects traversal and inconsistent imported totals", async () => {
    await expect(
      createDirectoryManifest([file("../escape.txt", "bad")]),
    ).rejects.toThrow(/unsafe/iu);
    const manifest = await createDirectoryManifest([file("safe.txt", "ok")]);
    const serialized = JSON.stringify({
      ...manifest,
      totals: { files: 1, bytes: 999 },
    });
    expect(() => parseDirectoryManifest(serialized)).toThrow(/totals/iu);
  });

  it("rejects case-normalized collisions and invalid timestamps on import", async () => {
    const manifest = await createDirectoryManifest([file("safe.txt", "ok")]);
    const duplicate = {
      ...manifest,
      entries: [
        manifest.entries[0],
        { ...manifest.entries[0], path: "SAFE.txt" },
      ],
      totals: { files: 2, bytes: manifest.totals.bytes * 2 },
    };
    expect(() => parseDirectoryManifest(JSON.stringify(duplicate))).toThrow(
      /collision/iu,
    );
    expect(() =>
      parseDirectoryManifest(
        JSON.stringify({
          ...manifest,
          entries: [{ ...manifest.entries[0], lastModified: "not-a-date" }],
        }),
      ),
    ).toThrow(/fields/iu);
  });
});

describe("bounded three-way merge", () => {
  it("combines non-overlapping line changes without conflict", () => {
    const result = mergeThreeWay({
      base: "one\ntwo\nthree\n",
      ours: "ONE\ntwo\nthree\n",
      theirs: "one\ntwo\nTHREE\n",
    });
    expect(result.clean).toBe(true);
    expect(result.text).toBe("ONE\ntwo\nTHREE\n");
  });

  it("emits explicit ours/base/theirs markers for overlapping changes", () => {
    const result = mergeThreeWay({
      base: "same\nvalue\n",
      ours: "same\nours\n",
      theirs: "same\ntheirs\n",
      oursName: "working.txt",
      theirsName: "incoming.txt",
    });
    expect(result.clean).toBe(false);
    expect(result.conflicts).toHaveLength(1);
    expect(result.text).toContain("<<<<<<< working.txt");
    expect(result.text).toContain("||||||| base");
    expect(result.text).toContain(">>>>>>> incoming.txt");
    expect(JSON.parse(result.report)).toMatchObject({
      schema: "de.add-ideas.diff-tools.merge-report.v1",
      clean: false,
    });
  });

  it("keeps conflict markers on their own lines when inputs lack final newlines", () => {
    const result = mergeThreeWay({
      base: "base",
      ours: "ours",
      theirs: "theirs",
    });
    expect(result.text).toBe(
      "<<<<<<< ours\nours\n||||||| base\nbase\n=======\ntheirs\n>>>>>>> theirs\n",
    );
  });
});