tts-workshop/packages/bgm/src/vite.unit.test.ts

import { describe, expect, it } from "vitest";
import * as path from "node:path";
import { fileURLToPath } from "node:url";
import { bgm } from "./vite.js";

const fixtureRoot = path.resolve(
  path.dirname(fileURLToPath(import.meta.url)),
  "__fixtures__",
);
const gamesRoot = path.join(fixtureRoot, "harbor");

/**
 * Vite 8 types plugin hooks as `ObjectHook`, which may be a plain function or
 * a `{ handler, order }` object. Our plugin uses plain functions, so cast the
 * hook to a callable for direct invocation in tests.
 */
type Callable<T> = T extends (...args: infer A) => infer R
  ? (...args: A) => R
  : never;

function resolveId(plugin: ReturnType<typeof bgm>, id: string): unknown {
  return (plugin.resolveId as Callable<typeof plugin.resolveId>)(
    id,
    undefined,
    {
      isEntry: false,
    },
  );
}

function load(plugin: ReturnType<typeof bgm>, id: string): unknown {
  return (plugin.load as Callable<typeof plugin.load>)(id, { ssr: false });
}

/** Parse the JSON payload out of an emitted `export default <json>` module. */
function parseModule(code: unknown): unknown {
  expect(String(code).startsWith("export default ")).toBe(true);
  return JSON.parse(String(code).slice("export default ".length));
}

describe("bgm vite plugin", () => {
  it("resolves bgm imports to the virtual module", () => {
    const plugin = bgm({ root: gamesRoot });
    expect(resolveId(plugin, "virtual:bgm/packages")).toBe(
      "\0bgm:virtual:bgm/packages",
    );
    expect(resolveId(plugin, "virtual:bgm/package/harbor")).toBe(
      "\0bgm:virtual:bgm/package/harbor",
    );
    expect(resolveId(plugin, "virtual:bgm/package/nope")).toBe(
      "\0bgm:virtual:bgm/package/nope",
    );
    expect(resolveId(plugin, "other")).toBeUndefined();
  });

  it("loads every package as a JSON module", () => {
    const plugin = bgm({ root: gamesRoot });
    const packages = parseModule(
      load(plugin, "\0bgm:virtual:bgm/packages"),
    ) as Array<Record<string, any>>;
    expect(packages).toHaveLength(1);
    expect(packages[0].meta.id).toBe("harbor");
    expect(packages[0].parts).toHaveProperty("token#wood");
  });

  it("loads a package as a JSON module", () => {
    const plugin = bgm({ root: gamesRoot });
    const pkg = parseModule(
      load(plugin, "\0bgm:virtual:bgm/package/harbor"),
    ) as Record<string, any>;
    expect(pkg.meta.id).toBe("harbor");
    expect(pkg.parts).toHaveProperty("token#wood");
    expect(pkg.surfaces).toHaveProperty("board#harbor");
  });

  it("serializes maps as plain objects, not Map instances", () => {
    const plugin = bgm({ root: gamesRoot });
    const pkg = parseModule(
      load(plugin, "\0bgm:virtual:bgm/package/harbor"),
    ) as Record<string, any>;

    // The emitted shape must be JSON-serializable: plain objects keyed by
    // `type#id`, not `Map`s (which `JSON.stringify` turns into `{}`).
    for (const key of ["parts", "surfaces", "setups", "dialogs"] as const) {
      expect(pkg[key]).not.toBeInstanceOf(Map);
      expect(pkg[key]).toEqual(expect.any(Object));
    }

    // Consumers read the collections with Object.values / Object.keys.
    expect(
      Object.values(pkg.parts)
        .map((p: any) => p.id)
        .sort(),
    ).toEqual(["grain", "wood"]);
    expect(Object.keys(pkg.surfaces)).toEqual(["board#harbor", "board#player"]);
    expect(Object.keys(pkg.setups)).toEqual(["game#main"]);
  });

  it("errors on an unknown package", () => {
    const plugin = bgm({ root: gamesRoot });
    expect(() => load(plugin, "\0bgm:virtual:bgm/package/unknown")).toThrow(
      /not found/,
    );
  });

  it("watches every source file for reloads", () => {
    const plugin = bgm({ root: gamesRoot });
    const watched: string[] = [];
    const context = { addWatchFile: (file: string) => watched.push(file) };
    // Vite 8 (rolldown) `buildStart` takes `(this, options)`; the plugin ignores
    // the options, so pass a placeholder.
    (plugin.buildStart as Callable<typeof plugin.buildStart>).call(
      context,
      {} as never,
    );

    // Every def file (real + virtual code blocks) is watched so edits
    // trigger a re-collect. The real markdown source must be watched too:
    // `defMap.files` only lists virtual code-block files, so without watching
    // the on-disk `.md` file the dev server would never notice an edit.
    expect(watched.length).toBeGreaterThan(0);
    expect(watched.some((f) => f.endsWith(".yaml"))).toBe(true);
    expect(watched.some((f) => f.endsWith(".csv"))).toBe(true);
    expect(watched.some((f) => f.endsWith(".md"))).toBe(true);
    expect(watched.every((f) => path.isAbsolute(f))).toBe(true);
  });
});