feat(fs/walk): WalkError class

[lino-levan]

closes #3023.

The concept is that if you want to catch an error and see what caused it, you should be able to use err.cause instanceof ErrorClassYouWantToCatch.

[kt3k]

@lino-levan Can you also add a simple test case which checks WalkError being thrown?

[lino-levan]

SGTM, I'll get around to it when I get around to it. Maybe tomorrow if I get the chance.

[lino-levan]

@kt3k I tried my hand at writing a test for this but can't think of a way for this to error out consistently (without relying on something like removing a folder after we already started walking it). Do you have any ideas?

[jsejcksn]

I tried my hand at writing a test for this but can't think of a way for this to error out consistently (without relying on something like removing a folder after we already started walking it). Do you have any ideas?

@lino-levan I just tested this locally and it reliably throws every run:

test.ts:

// deno test --allow-read=exampleRootTestDir --allow-write=exampleRootTestDir

import { assertRejects } from "https://deno.land/std@0.178.0/testing/asserts.ts";
import { walk } from "https://deno.land/std@0.178.0/fs/walk.ts";

Deno.test("throws", async () => {
  const dir = "exampleRootTestDir";

  await assertRejects(async () => {
    await Deno.mkdir(dir);
    for await (const _walkEntry of walk(dir)) await Deno.remove(dir);
  });
});

 % deno --version
deno 1.31.1 (release, aarch64-apple-darwin)
v8 11.0.226.13
typescript 4.9.4

% deno test --allow-read=exampleRootTestDir --allow-write=exampleRootTestDir
running 1 test from ./test.ts
throws ... ok (6ms)

ok | 1 passed | 0 failed (20ms)

Check out the testWalk function in the test file.

[lino-levan]

LGTM, thanks for your help on this PR!

[kt3k]

LGTM. Thanks! @lino-levan