assert: stricter ifError

This makes `assert.ifError` stricter by only accepting `null` and
`undefined` from now on. Before any truthy value was accepted.

PR-URL: #18247
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/assert.md

@@ -474,21 +474,23 @@ changes:
    pr-url: https://github.com/nodejs/node/pull/18247
    description: Instead of throwing the original error it is now wrapped into
                 a AssertionError that contains the full stack trace.
  - version: REPLACEME
    pr-url: https://github.com/nodejs/node/pull/18247
    description: Value may now only be `undefined` or `null`. Before any truthy
                 input was accepted.
-->
* `value` {any}

Throws `value` if `value` is truthy. This is useful when testing the `error`
argument in callbacks.
Throws `value` if `value` is not `undefined` or `null`. This is useful when
testing the `error` argument in callbacks.

```js
const assert = require('assert').strict;

assert.ifError(null);
// OK
assert.ifError(0);
// OK
assert.ifError(1);
// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: 1
// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: 0
assert.ifError('error');
// AssertionError [ERR_ASSERTION]: ifError got unwanted exception: 'error'
assert.ifError(new Error());

lib/assert.js

@@ -453,7 +453,7 @@ assert.doesNotThrow = function doesNotThrow(block, error, message) {
};

assert.ifError = function ifError(err) {
  if (err) {
  if (err !== null && err !== undefined) {
    let message = 'ifError got unwanted exception: ';
    if (typeof err === 'object' && typeof err.message === 'string') {
      if (err.message.length === 0 && err.constructor) {

test/parallel/test-assert-if-error.js

@@ -60,10 +60,16 @@ assert.throws(
  }
);

assert.throws(
  () => { assert.ifError(false); },
  {
    message: 'ifError got unwanted exception: false'
  }
);

assert.doesNotThrow(() => { assert.ifError(null); });
assert.doesNotThrow(() => { assert.ifError(); });
assert.doesNotThrow(() => { assert.ifError(undefined); });
assert.doesNotThrow(() => { assert.ifError(false); });

// https://github.com/nodejs/node-v0.x-archive/issues/2893
{

test/sequential/test-inspector-port-zero.js

@@ -16,8 +16,8 @@ function test(arg, port = '') {
  let stderr = '';
  proc.stdout.on('data', (data) => stdout += data);
  proc.stderr.on('data', (data) => stderr += data);
  proc.stdout.on('close', assert.ifError);
  proc.stderr.on('close', assert.ifError);
  proc.stdout.on('close', (hadErr) => assert(!hadErr));
  proc.stderr.on('close', (hadErr) => assert(!hadErr));
  proc.stderr.on('data', () => {
    if (!stderr.includes('\n')) return;
    assert(/Debugger listening on (.+)/.test(stderr));