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

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

@@ -0,0 +1,27 @@
+'use strict';
+
+var ERR_INVALID_OPT_VALUE = require('../../../errors').codes.ERR_INVALID_OPT_VALUE;
+
+function highWaterMarkFrom(options, isDuplex, duplexKey) {
+  return options.highWaterMark != null ? options.highWaterMark : isDuplex ? options[duplexKey] : null;
+}
+
+function getHighWaterMark(state, options, duplexKey, isDuplex) {
+  var hwm = highWaterMarkFrom(options, isDuplex, duplexKey);
+
+  if (hwm != null) {
+    if (!(isFinite(hwm) && Math.floor(hwm) === hwm) || hwm < 0) {
+      var name = isDuplex ? duplexKey : 'highWaterMark';
+      throw new ERR_INVALID_OPT_VALUE(name, hwm);
+    }
+
+    return Math.floor(hwm);
+  } // Default value
+
+
+  return state.objectMode ? 16 : 16 * 1024;
+}
+
+module.exports = {
+  getHighWaterMark: getHighWaterMark
+};