stream: finish must always follow error

When _write completes with an Error, 'finish' was emitted before
'error' if the callback was asynchronous. This commit restore the
previous behavior.
The logic is still less then ideal, because we call the write()
callback before emitting error if asynchronous, but after if
synchronous. This commit do not try to change the behavior.
This commit fixes a regression introduced by:
nodejs#13195.

Fixes: nodejs#13812

lib/_stream_writable.js

@@ -374,18 +374,26 @@ function doWrite(stream, state, writev, len, chunk, encoding, cb) {
 
 function onwriteError(stream, state, sync, er, cb) {
   --state.pendingcb;
-  if (sync)
-    process.nextTick(afterError, stream, state, cb, er);
-  else
-    afterError(stream, state, cb, er);
-
-  stream._writableState.errorEmitted = true;
-  stream.emit('error', er);
-}
 
-function afterError(stream, state, cb, err) {
-  cb(err);
-  finishMaybe(stream, state);
+  if (sync) {
+    // defer the callback if we are being called synchronously
+    // to avoid piling up things on the stack
+    process.nextTick(cb, er);
+    // this can emit finish, and it will always happen
+    // after error
+    process.nextTick(finishMaybe, stream, state);
+    stream._writableState.errorEmitted = true;
+    stream.emit('error', er);
+  } else {
+    // the caller expect this to happen before if
+    // it is async
+    cb(er);
+    stream._writableState.errorEmitted = true;
+    stream.emit('error', er);
+    // this can emit finish, but finish must
+    // always follow error
+    finishMaybe(stream, state);
+  }
 }
 
 function onwriteStateUpdate(state) {

test/parallel/test-stream-writable-write-writev-finish.js

@@ -0,0 +1,156 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const stream = require('stream');
+
+// ensure consistency between the finish event when using cork()
+// and writev and when not using them
+
+{
+  const writable = new stream.Writable();
+
+  writable._write = (chunks, encoding, cb) => {
+    cb(new Error('write test error'));
+  };
+
+  let firstError = false;
+  writable.on('finish', common.mustCall(function() {
+    assert.strictEqual(firstError, true);
+  }));
+
+  writable.on('prefinish', common.mustCall());
+
+  writable.on('error', common.mustCall((er) => {
+    assert.strictEqual(er.message, 'write test error');
+    firstError = true;
+  }));
+
+  writable.end('test');
+}
+
+{
+  const writable = new stream.Writable();
+
+  writable._write = (chunks, encoding, cb) => {
+    setImmediate(cb, new Error('write test error'));
+  };
+
+  let firstError = false;
+  writable.on('finish', common.mustCall(function() {
+    assert.strictEqual(firstError, true);
+  }));
+
+  writable.on('prefinish', common.mustCall());
+
+  writable.on('error', common.mustCall((er) => {
+    assert.strictEqual(er.message, 'write test error');
+    firstError = true;
+  }));
+
+  writable.end('test');
+}
+
+{
+  const writable = new stream.Writable();
+
+  writable._write = (chunks, encoding, cb) => {
+    cb(new Error('write test error'));
+  };
+
+  writable._writev = (chunks, cb) => {
+    cb(new Error('writev test error'));
+  };
+
+  let firstError = false;
+  writable.on('finish', common.mustCall(function() {
+    assert.strictEqual(firstError, true);
+  }));
+
+  writable.on('prefinish', common.mustCall());
+
+  writable.on('error', common.mustCall((er) => {
+    assert.strictEqual(er.message, 'writev test error');
+    firstError = true;
+  }));
+
+  writable.cork();
+  writable.write('test');
+
+  setImmediate(function() {
+    writable.end('test');
+  });
+}
+
+{
+  const writable = new stream.Writable();
+
+  writable._write = (chunks, encoding, cb) => {
+    setImmediate(cb, new Error('write test error'));
+  };
+
+  writable._writev = (chunks, cb) => {
+    setImmediate(cb, new Error('writev test error'));
+  };
+
+  let firstError = false;
+  writable.on('finish', common.mustCall(function() {
+    assert.strictEqual(firstError, true);
+  }));
+
+  writable.on('prefinish', common.mustCall());
+
+  writable.on('error', common.mustCall((er) => {
+    assert.strictEqual(er.message, 'writev test error');
+    firstError = true;
+  }));
+
+  writable.cork();
+  writable.write('test');
+
+  setImmediate(function() {
+    writable.end('test');
+  });
+}
+
+// Regression test for
+// https://github.com/nodejs/node/issues/13812
+
+{
+  const rs = new stream.Readable();
+  rs.push('ok');
+  rs.push(null);
+  rs._read = () => {};
+
+  const ws = new stream.Writable();
+  let firstError = false;
+
+  ws.on('finish', common.mustCall(function() {
+    assert.strictEqual(firstError, true);
+  }));
+  ws.on('error', common.mustCall(function() {
+    firstError = true;
+  }));
+
+  ws._write = (chunk, encoding, done) => {
+    setImmediate(done, new Error());
+  };
+  rs.pipe(ws);
+}
+
+{
+  const rs = new stream.Readable();
+  rs.push('ok');
+  rs.push(null);
+  rs._read = () => {};
+
+  const ws = new stream.Writable();
+
+  ws.on('finish', common.mustNotCall());
+  ws.on('error', common.mustCall());
+
+  ws._write = (chunk, encoding, done) => {
+    done(new Error());
+  };
+  rs.pipe(ws);
+}