stream: Writable.end(chunk) after end is an error

Calling end(data) calls write(data).  Doing this after end should
raise a 'write after end' error.

However, because end() calls were previously ignored on already
ended streams, this error was confusingly suppressed, even though the
data never is written, and cannot get to the other side.

This is a re-hash of 5222d19, but
without assuming that the data passed to end() is valid, and thus
breaking a bunch of tests.

lib/_stream_writable.js

@@ -304,10 +304,6 @@ Writable.prototype._write = function(chunk, cb) {
 Writable.prototype.end = function(chunk, encoding, cb) {
   var state = this._writableState;
 
-  // ignore unnecessary end() calls.
-  if (state.ending || state.ended || state.finished)
-    return;
-
   if (typeof chunk === 'function') {
     cb = chunk;
     chunk = null;
@@ -317,17 +313,26 @@ Writable.prototype.end = function(chunk, encoding, cb) {
     encoding = null;
   }
 
+  if (typeof chunk !== 'undefined' && chunk !== null)
+    this.write(chunk, encoding);
+
+  // ignore unnecessary end() calls.
+  if (!state.ending && !state.ended && !state.finished)
+    endWritable(this, state, cb);
+};
+
+function endWritable(stream, state, cb) {
   state.ending = true;
-  if (chunk)
-    this.write(chunk, encoding, cb);
-  else if (state.length === 0 && !state.finishing && !state.finished) {
+  if (state.length === 0 && !state.finishing) {
     state.finishing = true;
-    this.emit('finish');
+    stream.emit('finish');
     state.finished = true;
-    if (cb) process.nextTick(cb);
-  } else if (cb) {
-    this.once('finish', cb);
   }
-
+  if (cb) {
+    if (state.finished || state.finishing)
+      process.nextTick(cb);
+    else
+      stream.once('finish', cb);
+  }
   state.ended = true;
-};
+}

test/simple/test-stream2-writable.js

@@ -311,3 +311,19 @@ test('duplexes are pipable', function(t) {
   assert(!gotError);
   t.end();
 });
+
+test('end(chunk) two times is an error', function(t) {
+  var w = new W();
+  w._write = function() {};
+  var gotError = false;
+  w.on('error', function(er) {
+    gotError = true;
+    t.equal(er.message, 'write after end');
+  });
+  w.end('this is the end');
+  w.end('and so is this');
+  process.nextTick(function() {
+    assert(gotError);
+    t.end();
+  });
+});