test: tests for _readableStream.awaitDrain

Fixes: https://github.com/nodejs/node/issues/8684
PR-URL: https://github.com/nodejs/node/pull/8914
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

1 files changed, 19 insertions, 0 deletions

diff --git a/test/parallel/test-stream-pipe-await-drain.js b/test/parallel/test-stream-pipe-await-drain.js
index fba99ed456..fc822bb60b 100644
--- a/test/parallel/test-stream-pipe-await-drain.js
+++ b/test/parallel/test-stream-pipe-await-drain.js
@@ -1,12 +1,14 @@
 '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
@@ -19,7 +21,10 @@ 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.
@@ -29,12 +34,26 @@ writer1.once('chunk-received', function() {
 
 // 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);