index.ts

import { resolve } from "node:path";
import { readAllFiles } from "./readAllFiles.ts";

/**
 * Glob - ExperimentalWarning  --disable-warning=ExperimentalWarning NODE_OPTIONS=
 * Typescript --experimental-transform-types --no-experimental-strip-types. import type
 * Test
 */
export const folder = resolve(import.meta.dirname, process.env.ROOT_FOLDER!);

const output = await readAllFiles(folder);

console.log("promies", { output });

readAllFiles.test.ts

import assert from "assert";
import test from "node:test";

async function* asyncGenerator() {
  yield "file1.json";
  yield "file2.json";
}

test("should return files content", async (t) => {
  t.mock.module("node:fs/promises", {
    namedExports: {
      glob: asyncGenerator,
      readFile: (path) => `{"${path}": "value"}`,
    },
  });

  const { readAllFiles } = await import("./readAllFiles.ts");

  const output = await readAllFiles("");

  assert.deepEqual(output, { "file1.json": "value", "file2.json": "value" });
});

readAllFiles.ts

import { glob, readFile } from "fs/promises";
import type { Dictionnary } from "./type.ts";

export const readAllFiles = async (folder: string) => {
  let output: Dictionnary = {};

  for await (let path of glob(`${folder}/**/*.json`)) {
    const content = await readFile(path);
    output = {
      ...output,
      ...JSON.parse(content.toString()),
    };
  }

  return output;
};

type.ts

export type Dictionnary = Record<string, unknown>;