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var expect = require('chai').expect;
var util = require('./util');
var Flow = require('../lib/protocol/flow').Flow;
var MAX_PAYLOAD_SIZE = 16384;
function createFlow(log) {
var flowControlId = util.random(10, 100);
var flow = new Flow(flowControlId);
flow._log = util.log.child(log || {});
return flow;
}
describe('flow.js', function() {
describe('Flow class', function() {
var flow;
beforeEach(function() {
flow = createFlow();
});
describe('._receive(frame, callback) method', function() {
it('is called when there\'s a frame in the input buffer to be consumed', function(done) {
var frame = { type: 'PRIORITY', flags: {}, priority: 1 };
flow._receive = function _receive(receivedFrame, callback) {
expect(receivedFrame).to.equal(frame);
callback();
};
flow.write(frame, done);
});
it('has to be overridden by the child class, otherwise it throws', function() {
expect(flow._receive.bind(flow)).to.throw(Error);
});
});
describe('._send() method', function() {
it('is called when the output buffer should be filled with more frames and the flow' +
'control queue is empty', function() {
var notFlowControlledFrame = { type: 'PRIORITY', flags: {}, priority: 1 };
flow._send = function _send() {
this.push(notFlowControlledFrame);
};
expect(flow.read()).to.equal(notFlowControlledFrame);
flow._window = 0;
flow._queue.push({ type: 'DATA', flags: {}, data: { length: 1 } });
var frame = flow.read();
while (frame.type === notFlowControlledFrame.type) frame = flow.read();
expect(frame.type).to.equal('BLOCKED');
expect(flow.read()).to.equal(null);
});
it('has to be overridden by the child class, otherwise it throws', function() {
expect(flow._send.bind(flow)).to.throw(Error);
});
});
describe('._increaseWindow(size) method', function() {
it('should increase `this._window` by `size`', function() {
flow._send = util.noop;
flow._window = 0;
var increase1 = util.random(0,100);
var increase2 = util.random(0,100);
flow._increaseWindow(increase1);
flow._increaseWindow(increase2);
expect(flow._window).to.equal(increase1 + increase2);
flow._increaseWindow(Infinity);
expect(flow._window).to.equal(Infinity);
});
it('should emit error when increasing with a finite `size` when `_window` is infinite', function() {
flow._send = util.noop;
flow._increaseWindow(Infinity);
var increase = util.random(1,100);
expect(flow._increaseWindow.bind(flow, increase)).to.throw('Uncaught, unspecified "error" event.');
});
it('should emit error when `_window` grows over the window limit', function() {
var WINDOW_SIZE_LIMIT = Math.pow(2, 31) - 1;
flow._send = util.noop;
flow._window = 0;
flow._increaseWindow(WINDOW_SIZE_LIMIT);
expect(flow._increaseWindow.bind(flow, 1)).to.throw('Uncaught, unspecified "error" event.');
});
});
describe('.read() method', function() {
describe('when the flow control queue is not empty', function() {
it('should return the first item in the queue if the window is enough', function() {
var priorityFrame = { type: 'PRIORITY', flags: {}, priority: 1 };
var dataFrame = { type: 'DATA', flags: {}, data: { length: 10 } };
flow._send = util.noop;
flow._window = 10;
flow._queue = [priorityFrame, dataFrame];
expect(flow.read()).to.equal(priorityFrame);
expect(flow.read()).to.equal(dataFrame);
});
it('should also split DATA frames when needed', function() {
var buffer = new Buffer(10);
var dataFrame = { type: 'DATA', flags: {}, stream: util.random(0, 100), data: buffer };
flow._send = util.noop;
flow._window = 5;
flow._queue = [dataFrame];
var expectedFragment = { flags: {}, type: 'DATA', stream: dataFrame.stream, data: buffer.slice(0,5) };
expect(flow.read()).to.deep.equal(expectedFragment);
expect(dataFrame.data).to.deep.equal(buffer.slice(5));
});
});
});
describe('.push(frame) method', function() {
it('should push `frame` into the output queue or the flow control queue', function() {
var priorityFrame = { type: 'PRIORITY', flags: {}, priority: 1 };
var dataFrame = { type: 'DATA', flags: {}, data: { length: 10 } };
flow._window = 10;
flow.push(dataFrame); // output queue
flow.push(dataFrame); // flow control queue, because of depleted window
flow.push(priorityFrame); // flow control queue, because it's not empty
expect(flow.read()).to.be.equal(dataFrame);
expect(flow._queue[0]).to.be.equal(dataFrame);
expect(flow._queue[1]).to.be.equal(priorityFrame);
});
});
describe('.write() method', function() {
it('call with a DATA frame should trigger sending WINDOW_UPDATE if remote flow control is not' +
'disabled', function(done) {
flow._window = 100;
flow._send = util.noop;
flow._receive = function(frame, callback) {
callback();
};
var buffer = new Buffer(util.random(10, 100));
flow.write({ type: 'DATA', flags: {}, data: buffer });
flow.once('readable', function() {
expect(flow.read()).to.be.deep.equal({
type: 'WINDOW_UPDATE',
flags: {},
stream: flow._flowControlId,
window_size: buffer.length
});
done();
});
});
});
});
describe('test scenario', function() {
var flow1, flow2;
beforeEach(function() {
flow1 = createFlow({ flow: 1 });
flow2 = createFlow({ flow: 2 });
flow1._flowControlId = flow2._flowControlId;
flow1._send = flow2._send = util.noop;
flow1._receive = flow2._receive = function(frame, callback) { callback(); };
});
describe('sending a large data stream', function() {
it('should work as expected', function(done) {
// Sender side
var frameNumber = util.random(5, 8);
var input = [];
flow1._send = function _send() {
if (input.length >= frameNumber) {
this.push({ type: 'DATA', flags: { END_STREAM: true }, data: new Buffer(0) });
this.push(null);
} else {
var buffer = new Buffer(util.random(1000, 100000));
input.push(buffer);
this.push({ type: 'DATA', flags: {}, data: buffer });
}
};
// Receiver side
var output = [];
flow2._receive = function _receive(frame, callback) {
if (frame.type === 'DATA') {
expect(frame.data.length).to.be.lte(MAX_PAYLOAD_SIZE);
output.push(frame.data);
}
if (frame.flags.END_STREAM) {
this.emit('end_stream');
}
callback();
};
// Checking results
flow2.on('end_stream', function() {
input = util.concat(input);
output = util.concat(output);
expect(input).to.deep.equal(output);
done();
});
// Start piping
flow1.pipe(flow2).pipe(flow1);
});
});
describe('when running out of window', function() {
it('should send a BLOCKED frame', function(done) {
// Sender side
var frameNumber = util.random(5, 8);
var input = [];
flow1._send = function _send() {
if (input.length >= frameNumber) {
this.push({ type: 'DATA', flags: { END_STREAM: true }, data: new Buffer(0) });
this.push(null);
} else {
var buffer = new Buffer(util.random(1000, 100000));
input.push(buffer);
this.push({ type: 'DATA', flags: {}, data: buffer });
}
};
// Receiver side
// Do not send WINDOW_UPDATESs except when the other side sends BLOCKED
var output = [];
flow2._restoreWindow = util.noop;
flow2._receive = function _receive(frame, callback) {
if (frame.type === 'DATA') {
expect(frame.data.length).to.be.lte(MAX_PAYLOAD_SIZE);
output.push(frame.data);
}
if (frame.flags.END_STREAM) {
this.emit('end_stream');
}
if (frame.type === 'BLOCKED') {
setTimeout(function() {
this._push({
type: 'WINDOW_UPDATE',
flags: {},
stream: this._flowControlId,
window_size: this._received
});
this._received = 0;
}.bind(this), 20);
}
callback();
};
// Checking results
flow2.on('end_stream', function() {
input = util.concat(input);
output = util.concat(output);
expect(input).to.deep.equal(output);
done();
});
// Start piping
flow1.pipe(flow2).pipe(flow1);
});
});
});
});
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