test: Add test for stream flow stalled after unpipe()

test/parallel/test-stream-unpipe-stalls-flow.js

@@ -0,0 +1,111 @@
+// Copyright Joyent, Inc. and other Node contributors.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and associated documentation files (the
+// "Software"), to deal in the Software without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Software, and to permit
+// persons to whom the Software is furnished to do so, subject to the
+// following conditions:
+//
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN
+// NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
+// DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
+// USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+'use strict';
+require('../common');
+const assert = require('assert');
+const stream = require('stream');
+const util = require('util');
+
+// Construct a chunks array, for consuming in the test.
+const numTestChunks = 30;
+const chunks = [];
+for (let i = 1; i <= numTestChunks; i++) {
+  chunks.push(String(i));
+}
+
+// Define a Writable class that consumes data.
+function TestWriter() {
+  stream.Writable.call(this);
+}
+util.inherits(TestWriter, stream.Writable);
+
+TestWriter.prototype._write = function(buffer, encoding, callback) {
+  callback(null);
+};
+
+// Define a Readable class that generates data, from the `chunks` array.
+function TestReader(length) {
+  stream.Readable.call(this);
+}
+util.inherits(TestReader, stream.Readable);
+
+TestReader.prototype._read = function(size) {
+  if (chunks.length) {
+    const chunk = chunks.shift();
+    this.push(chunk);
+    this.emit('_chunkRead', chunk);
+  } else {
+    this.push(null);
+
+    const reader = this;
+    // Allow any pending `data` events to trigger, first.
+    process.nextTick(function() {
+      reader.emit('_readFinished');
+    });
+  }
+};
+
+let destUnpiped = false;
+
+const dest = new TestWriter();
+const src = new TestReader();
+
+const counter = {
+  numDataEvents: 0,
+  numChunksRead: 0
+};
+
+// Count `data` events.
+src.on('data', function() {
+  counter.numDataEvents++;
+});
+
+// Count internal `_chunkRead` events.
+src.on('_chunkRead', function() {
+  counter.numChunksRead++;
+
+  // After 10 chunk reads, unpipe dest.
+  if (counter.numChunksRead === 10) {
+    src.unpipe(dest);
+  }
+});
+
+dest.on('unpipe', function() {
+  destUnpiped = true;
+});
+
+src.pipe(dest);
+
+src.on('_readFinished', function() {
+  // Destination was unpiped.
+  assert.strictEqual(destUnpiped, true);
+  // The initial `data` event listener is still attached.
+  assert.strictEqual(src.listeners('data').length, 1);
+  // The number of _chunkRead events recorded, must match number of test chunks.
+  assert.strictEqual(counter.numChunksRead, numTestChunks);
+  // The number of data events recorded, must match number of test chunks.
+  assert.strictEqual(counter.numDataEvents, numTestChunks);
+});
+
+process.on('exit', function() {
+  console.log('ok');
+});