Assertion function to perform SnapshotTest in Deno with update option

assertSnapshot.ts

import {
  assertEquals,
  equal,
} from "https://deno.land/std@0.132.0/testing/asserts.ts";
import { copy } from "https://deno.land/std@0.132.0/fs/mod.ts";

export const assertSnapshot = async (
  receivedPath: string,
  expectedPath: string
) => {
  const [received, expected] = await Promise.all([
    Deno.readTextFile(receivedPath),
    Deno.readTextFile(expectedPath),
  ]);
  if (Deno.args.includes("update_snapshot")) {
    if (equal(received, expected)) return;
    await copy(receivedPath, expectedPath, { overwrite: true });
  } else {
    assertEquals(received, expected);
  }
};

shell

#!/bin/bash

deno test test.ts --allow-read --allow-write
# or
deno test test.ts --allow-read --allow-write -- update_snapshot # with update snapshots

test.ts

Deno.test(async()=>{
  const tmp = await Deno.makeTempFile();
  //write tmp file
  ... 
  await assertSnapshot(tmp, "test.snapshot");
})