node/test/parallel/test-stream-pipe-await-drain.js
Rich Trott 380929ec0c test: remove common.noop
This change removes `common.noop` from the Node.js internal testing
common module.

Over the last few weeks, I've grown to dislike the `common.noop`
abstraction.

First, new (and experienced) contributors are unaware of it and so it
results in a large number of low-value nits on PRs. It also increases
the number of things newcomers and infrequent contributors have to be
aware of to be effective on the project.

Second, it is confusing. Is it a singleton/property or a getter? Which
should be expected? This can lead to subtle and hard-to-find bugs. (To
my knowledge, none have landed on master. But I also think it's only a
matter of time.)

Third, the abstraction is low-value in my opinion. What does it really
get us? A case could me made that it is without value at all.

Lastly, and this is minor, but the abstraction is wordier than not using
the abstraction. `common.noop` doesn't save anything over `() => {}`.

So, I propose removing it.

PR-URL: https://github.com/nodejs/node/pull/12822
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Refael Ackermann <refack@gmail.com>
2017-07-03 11:39:35 -07:00

60 lines
1.7 KiB
JavaScript

'use strict';
const common = require('../common');
const stream = require('stream');
const assert = require('assert');
// This is very similar to test-stream-pipe-cleanup-pause.js.
const reader = new stream.Readable();
const writer1 = new stream.Writable();
const writer2 = new stream.Writable();
const writer3 = new stream.Writable();
// 560000 is chosen here because it is larger than the (default) highWaterMark
// and will cause `.write()` to return false
// See: https://github.com/nodejs/node/issues/5820
const buffer = Buffer.allocUnsafe(560000);
reader._read = () => {};
writer1._write = common.mustCall(function(chunk, encoding, cb) {
this.emit('chunk-received');
cb();
}, 1);
writer1.once('chunk-received', function() {
assert.strictEqual(reader._readableState.awaitDrain, 0,
'initial value is not 0');
setImmediate(function() {
// This one should *not* get through to writer1 because writer2 is not
// "done" processing.
reader.push(buffer);
});
});
// A "slow" consumer:
writer2._write = common.mustCall(function(chunk, encoding, cb) {
assert.strictEqual(
reader._readableState.awaitDrain, 1,
'awaitDrain isn\'t 1 after first push'
);
// Not calling cb here to "simulate" slow stream.
// This should be called exactly once, since the first .write() call
// will return false.
}, 1);
writer3._write = common.mustCall(function(chunk, encoding, cb) {
assert.strictEqual(
reader._readableState.awaitDrain, 2,
'awaitDrain isn\'t 2 after second push'
);
// Not calling cb here to "simulate" slow stream.
// This should be called exactly once, since the first .write() call
// will return false.
}, 1);
reader.pipe(writer1);
reader.pipe(writer2);
reader.pipe(writer3);
reader.push(buffer);