A simple helper to test functions not-exported but with _ prefix

deno_ts_testing_private_func_test.ts

// A simple helper to test functions not-exported but with _ prefix
const privateCases = async function (flpath: string, cases: Function) {
  const decoder = new TextDecoder("utf-8");
  let body = decoder.decode(await Deno.readFile(flpath));
  body = body.replace(/\nfunction _/g, "\nexport function _");
  const tmppath = flpath.replace(/([^\/]+)$/, "~$1"),
    encoder = new TextEncoder();
  await Deno.writeFile(tmppath, encoder.encode(body));

  cases(await import(tmppath));

  await Deno.remove(tmppath);
};

// Usage example
await privateCases("./hello.ts", (m: any) => {
  Deno.test("Hello not-exported _demo", () => {
    const result = m._demo();
    // ...
  });
});