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test: stream readable needReadable state

PR-URL: #10241
Ref: #8683
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Italo A. Casas <me@italoacasas.com>
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joyeecheung authored and italoacasas committed Dec 12, 2016
1 parent eceef76 commit 3daa4b1f76ed413fe984c514c30e4f7bd5abb95e
Showing with 96 additions and 0 deletions.
  1. +96 −0 test/parallel/test-stream-readable-needReadable.js
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'use strict';
const common = require('../common');
const assert = require('assert');
const Readable = require('stream').Readable;

const readable = new Readable({
read: () => {}
});

// Initialized to false.
assert.strictEqual(readable._readableState.needReadable, false);

readable.on('readable', common.mustCall(() => {
// When the readable event fires, needReadable is reset.
assert.strictEqual(readable._readableState.needReadable, false);
readable.read();
}));

// If a readable listener is attached, then a readable event is needed.
assert.strictEqual(readable._readableState.needReadable, true);

readable.push('foo');
readable.push(null);

readable.on('end', common.mustCall(() => {
// No need to emit readable anymore when the stream ends.
assert.strictEqual(readable._readableState.needReadable, false);
}));

const asyncReadable = new Readable({
read: () => {}
});

asyncReadable.on('readable', common.mustCall(() => {
if (asyncReadable.read() !== null) {
// After each read(), the buffer is empty.
// If the stream doesn't end now,
// then we need to notify the reader on future changes.
assert.strictEqual(asyncReadable._readableState.needReadable, true);
}
}, 3));

process.nextTick(common.mustCall(() => {
asyncReadable.push('foooo');
}));
process.nextTick(common.mustCall(() => {
asyncReadable.push('bar');
}));
process.nextTick(common.mustCall(() => {
asyncReadable.push(null);
}));

const flowing = new Readable({
read: () => {}
});

// Notice this must be above the on('data') call.
flowing.push('foooo');
flowing.push('bar');
flowing.push('quo');
process.nextTick(common.mustCall(() => {
flowing.push(null);
}));

// When the buffer already has enough data, and the stream is
// in flowing mode, there is no need for the readable event.
flowing.on('data', common.mustCall(function(data) {
assert.strictEqual(flowing._readableState.needReadable, false);
}, 3));

const slowProducer = new Readable({
read: () => {}
});

slowProducer.on('readable', common.mustCall(() => {
if (slowProducer.read(8) === null) {
// The buffer doesn't have enough data, and the stream is not ened,
// we need to notify the reader when data arrives.
assert.strictEqual(slowProducer._readableState.needReadable, true);
} else {
assert.strictEqual(slowProducer._readableState.needReadable, false);
}
}, 4));

process.nextTick(common.mustCall(() => {
slowProducer.push('foo');
}));
process.nextTick(common.mustCall(() => {
slowProducer.push('foo');
}));
process.nextTick(common.mustCall(() => {
slowProducer.push('foo');
}));
process.nextTick(common.mustCall(() => {
slowProducer.push(null);
}));

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