denoland-deno/cli/js/truncate_test.ts

// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
import { testPerm, assertEquals } from "./test_util.ts";

function readDataSync(name: string): string {
  const data = Deno.readFileSync(name);
  const decoder = new TextDecoder("utf-8");
  const text = decoder.decode(data);
  return text;
}

async function readData(name: string): Promise<string> {
  const data = await Deno.readFile(name);
  const decoder = new TextDecoder("utf-8");
  const text = decoder.decode(data);
  return text;
}

testPerm({ read: true, write: true }, function truncateSyncSuccess(): void {
  const enc = new TextEncoder();
  const d = enc.encode("Hello");
  const filename = Deno.makeTempDirSync() + "/test_truncateSync.txt";
  Deno.writeFileSync(filename, d);
  Deno.truncateSync(filename, 20);
  let data = readDataSync(filename);
  assertEquals(data.length, 20);
  Deno.truncateSync(filename, 5);
  data = readDataSync(filename);
  assertEquals(data.length, 5);
  Deno.truncateSync(filename, -5);
  data = readDataSync(filename);
  assertEquals(data.length, 0);
  Deno.removeSync(filename);
});

testPerm({ read: true, write: true }, async function truncateSuccess(): Promise<
  void
> {
  const enc = new TextEncoder();
  const d = enc.encode("Hello");
  const filename = Deno.makeTempDirSync() + "/test_truncate.txt";
  await Deno.writeFile(filename, d);
  await Deno.truncate(filename, 20);
  let data = await readData(filename);
  assertEquals(data.length, 20);
  await Deno.truncate(filename, 5);
  data = await readData(filename);
  assertEquals(data.length, 5);
  await Deno.truncate(filename, -5);
  data = await readData(filename);
  assertEquals(data.length, 0);
  await Deno.remove(filename);
});

testPerm({ write: false }, function truncateSyncPerm(): void {
  let err;
  try {
    Deno.mkdirSync("/test_truncateSyncPermission.txt");
  } catch (e) {
    err = e;
  }
  assertEquals(err.kind, Deno.ErrorKind.PermissionDenied);
  assertEquals(err.name, "PermissionDenied");
});

testPerm({ write: false }, async function truncatePerm(): Promise<void> {
  let err;
  try {
    await Deno.mkdir("/test_truncatePermission.txt");
  } catch (e) {
    err = e;
  }
  assertEquals(err.kind, Deno.ErrorKind.PermissionDenied);
  assertEquals(err.name, "PermissionDenied");
});