added unit testing, and started implementing unit tests...phew

node_modules/readable-stream/lib/internal/streams/destroy.js

@@ -0,0 +1,85 @@
+'use strict'; // undocumented cb() API, needed for core, not for public API
+
+function destroy(err, cb) {
+  var _this = this;
+
+  var readableDestroyed = this._readableState && this._readableState.destroyed;
+  var writableDestroyed = this._writableState && this._writableState.destroyed;
+
+  if (readableDestroyed || writableDestroyed) {
+    if (cb) {
+      cb(err);
+    } else if (err && (!this._writableState || !this._writableState.errorEmitted)) {
+      process.nextTick(emitErrorNT, this, err);
+    }
+
+    return this;
+  } // we set destroyed to true before firing error callbacks in order
+  // to make it re-entrance safe in case destroy() is called within callbacks
+
+
+  if (this._readableState) {
+    this._readableState.destroyed = true;
+  } // if this is a duplex stream mark the writable part as destroyed as well
+
+
+  if (this._writableState) {
+    this._writableState.destroyed = true;
+  }
+
+  this._destroy(err || null, function (err) {
+    if (!cb && err) {
+      process.nextTick(emitErrorAndCloseNT, _this, err);
+
+      if (_this._writableState) {
+        _this._writableState.errorEmitted = true;
+      }
+    } else if (cb) {
+      process.nextTick(emitCloseNT, _this);
+      cb(err);
+    } else {
+      process.nextTick(emitCloseNT, _this);
+    }
+  });
+
+  return this;
+}
+
+function emitErrorAndCloseNT(self, err) {
+  emitErrorNT(self, err);
+  emitCloseNT(self);
+}
+
+function emitCloseNT(self) {
+  if (self._writableState && !self._writableState.emitClose) return;
+  if (self._readableState && !self._readableState.emitClose) return;
+  self.emit('close');
+}
+
+function undestroy() {
+  if (this._readableState) {
+    this._readableState.destroyed = false;
+    this._readableState.reading = false;
+    this._readableState.ended = false;
+    this._readableState.endEmitted = false;
+  }
+
+  if (this._writableState) {
+    this._writableState.destroyed = false;
+    this._writableState.ended = false;
+    this._writableState.ending = false;
+    this._writableState.finalCalled = false;
+    this._writableState.prefinished = false;
+    this._writableState.finished = false;
+    this._writableState.errorEmitted = false;
+  }
+}
+
+function emitErrorNT(self, err) {
+  self.emit('error', err);
+}
+
+module.exports = {
+  destroy: destroy,
+  undestroy: undestroy
+};