feat(smartduplex): improve backpressure handling and web/node stream interoperability

test/test.streamwrapper.ts

@@ -0,0 +1,70 @@
+import { expect, tap } from '@push.rocks/tapbundle';
+import * as fs from 'fs';
+import { StreamWrapper, SmartDuplex } from '../ts/index.js';
+
+tap.test('StreamWrapper: should pipe read to write', async () => {
+  const wrapper = new StreamWrapper([
+    fs.createReadStream('./test/assets/test.md'),
+    fs.createWriteStream('./test/assets/testCopy.md'),
+  ]);
+  await wrapper.run();
+});
+
+tap.test('StreamWrapper: should propagate errors', async (tools) => {
+  const failingStream = new SmartDuplex<Buffer, Buffer>({
+    writeFunction: async () => {
+      throw new Error('intentional error');
+    },
+  });
+
+  const wrapper = new StreamWrapper([
+    fs.createReadStream('./test/assets/test.md'),
+    failingStream,
+  ]);
+
+  let errorCaught = false;
+  try {
+    await wrapper.run();
+  } catch (err) {
+    errorCaught = true;
+    expect(err.message).toEqual('intentional error');
+  }
+  expect(errorCaught).toBeTrue();
+});
+
+tap.test('StreamWrapper: streamStarted should resolve', async () => {
+  const wrapper = new StreamWrapper([
+    fs.createReadStream('./test/assets/test.md'),
+    fs.createWriteStream('./test/assets/testCopy.md'),
+  ]);
+
+  const runPromise = wrapper.run();
+  await wrapper.streamStarted();
+  await runPromise;
+});
+
+tap.test('StreamWrapper: onCustomEvent should fire', async (tools) => {
+  const results: string[] = [];
+
+  const emitter = new SmartDuplex<Buffer, Buffer>({
+    writeFunction: async (chunk, streamTools) => {
+      (emitter as any).emit('custom-progress', 'progress');
+      return chunk;
+    },
+  });
+
+  const wrapper = new StreamWrapper([
+    fs.createReadStream('./test/assets/test.md'),
+    emitter,
+    fs.createWriteStream('./test/assets/testCopy.md'),
+  ]);
+
+  wrapper.onCustomEvent('custom-progress', () => {
+    results.push('fired');
+  });
+
+  await wrapper.run();
+  expect(results.length).toBeGreaterThan(0);
+});
+
+export default tap.start();