fix(core): update

test/backpressure.ts

@@ -0,0 +1,57 @@
+import { SmartDuplex, type ISmartDuplexOptions, StreamWrapper } from '../ts/index.js';
+
+import * as smartdelay from '@push.rocks/smartdelay';
+
+async function testBackpressure() {
+  const stream1 = new SmartDuplex({
+    objectMode: true,
+    handleBackpressure: true,
+    writeFunction: async (chunk, tools) => {
+      console.log(`processed chunk ${chunk} in stream 1`);
+      return chunk; // Fast processing
+    }
+  });
+  const stream2 = new SmartDuplex({
+    objectMode: true,
+    handleBackpressure: true,
+    writeFunction: async (chunk, tools) => {
+      await new Promise(resolve => setTimeout(resolve, 100)); // Slow processing
+      console.log(`processed chunk ${chunk} in stream 2`);
+      return chunk;
+    }
+  }); // This stream processes data more slowly
+  const stream3 = new SmartDuplex({
+    handleBackpressure: false,
+    writeFunction: async (chunk, tools) => {
+      console.log(`finished chunk ${chunk} in stream 3`);
+    }
+  });
+
+  stream1.pipe(stream2).pipe(stream3);
+
+  let backpressured = false;
+  for (let i = 1; i < 100; i++) {
+    const canContinue = stream1.write(`Chunk ${i}`, 'utf8');
+    if (!canContinue) {
+      backpressured = true;
+      console.log(`Backpressure at chunk ${i}`);
+    }
+  }
+
+  stream1.end();
+
+  stream1.on('finish', () => {
+    console.log('Stream 1 finished processing.');
+  });
+  stream2.on('finish', () => {
+    console.log('Stream 2 finished processing.');
+  });
+  stream3.on('finish', () => {
+    console.log('Stream 3 finished processing.');
+    if (!backpressured) {
+      console.log('No backpressure was observed.');
+    }
+  });
+}
+
+testBackpressure();