smartstream/test/test.smartduplex.ts

import { expect, tap } from '@push.rocks/tapbundle';
import * as fs from 'fs';
import * as smartstream from '../ts/index.js';
import { SmartDuplex } from '../ts/smartstream.classes.smartduplex.js';

// =============================================
// Constructor
// =============================================

tap.test('SmartDuplex: should construct with no options', async () => {
  const duplex = new SmartDuplex();
  expect(duplex).toBeInstanceOf(SmartDuplex);
});

tap.test('SmartDuplex: should construct with options', async () => {
  const duplex = new SmartDuplex({
    objectMode: true,
    writeFunction: async (chunk) => chunk,
  });
  expect(duplex).toBeInstanceOf(SmartDuplex);
});

// =============================================
// fromBuffer
// =============================================

tap.test('SmartDuplex: should create from a Buffer', async () => {
  const bufferData = Buffer.from('This is a test buffer');
  const stream = SmartDuplex.fromBuffer(bufferData, {});

  let receivedData = Buffer.alloc(0);

  return new Promise<void>((resolve) => {
    stream.on('data', (chunk: Buffer) => {
      receivedData = Buffer.concat([receivedData, chunk]);
    });
    stream.on('end', () => {
      expect(receivedData.toString()).toEqual(bufferData.toString());
      resolve();
    });
  });
});

// =============================================
// writeFunction
// =============================================

tap.test('SmartDuplex: should transform chunks via writeFunction', async (tools) => {
  const results: string[] = [];
  const transform = new SmartDuplex<string, string>({
    objectMode: true,
    writeFunction: async (chunk) => {
      return chunk.toUpperCase();
    },
  });

  const done = tools.defer();

  transform.on('data', (chunk: string) => {
    results.push(chunk);
  });

  transform.on('end', () => {
    expect(results).toContain('HELLO');
    expect(results).toContain('WORLD');
    done.resolve();
  });

  transform.write('hello');
  transform.write('world');
  transform.end();
  await done.promise;
});

tap.test('SmartDuplex: writeFunction returning undefined should not push', async (tools) => {
  const results: any[] = [];
  const transform = new SmartDuplex<string, string>({
    objectMode: true,
    writeFunction: async () => {
      return undefined;
    },
  });

  const done = tools.defer();

  transform.on('data', (chunk: any) => {
    results.push(chunk);
  });

  transform.on('end', () => {
    expect(results.length).toEqual(0);
    done.resolve();
  });

  transform.write('hello');
  transform.end();
  await done.promise;
});

// =============================================
// tools.push — multiple outputs
// =============================================

tap.test('SmartDuplex: should emit multiple chunks via tools.push', async (tools) => {
  const results: string[] = [];
  const splitter = new SmartDuplex<string, string>({
    objectMode: true,
    writeFunction: async (chunk, streamTools) => {
      const words = chunk.split(' ');
      for (const word of words) {
        await streamTools.push(word);
      }
    },
  });

  const done = tools.defer();

  splitter.on('data', (chunk: string) => results.push(chunk));

  splitter.on('end', () => {
    expect(results).toContain('hello');
    expect(results).toContain('beautiful');
    expect(results).toContain('world');
    done.resolve();
  });

  splitter.write('hello beautiful world');
  splitter.end();
  await done.promise;
});

// =============================================
// finalFunction
// =============================================

tap.test('SmartDuplex: should emit final chunk via finalFunction', async (tools) => {
  const results: string[] = [];
  let count = 0;

  const aggregator = new SmartDuplex<string, string>({
    objectMode: true,
    writeFunction: async () => {
      count++;
      return undefined;
    },
    finalFunction: async () => {
      return `total: ${count}`;
    },
  });

  const done = tools.defer();

  aggregator.on('data', (chunk: string) => results.push(chunk));

  aggregator.on('end', () => {
    expect(results.length).toEqual(1);
    expect(results[0]).toEqual('total: 2');
    done.resolve();
  });

  aggregator.write('a');
  aggregator.write('b');
  aggregator.end();
  await done.promise;
});

tap.test('SmartDuplex: finalFunction can push multiple chunks via tools.push', async (tools) => {
  const results: string[] = [];

  const stream = new SmartDuplex<string, string>({
    objectMode: true,
    writeFunction: async (chunk) => chunk,
    finalFunction: async (streamTools) => {
      await streamTools.push('final1');
      await streamTools.push('final2');
    },
  });

  const done = tools.defer();

  stream.on('data', (chunk: string) => results.push(chunk));

  stream.on('end', () => {
    expect(results).toContain('hello');
    expect(results).toContain('final1');
    expect(results).toContain('final2');
    done.resolve();
  });

  stream.write('hello');
  stream.end();
  await done.promise;
});

// =============================================
// truncate
// =============================================

tap.test('SmartDuplex: should truncate stream early', async (tools) => {
  const results: string[] = [];

  const limiter = new SmartDuplex<string, string>({
    objectMode: true,
    writeFunction: async (chunk, streamTools) => {
      if (chunk === 'STOP') {
        streamTools.truncate();
        return undefined;
      }
      return chunk;
    },
  });

  const done = tools.defer();

  limiter.on('data', (chunk: string) => results.push(chunk));

  limiter.on('end', () => {
    expect(results).toContain('a');
    expect(results).toContain('b');
    expect(results).not.toContain('STOP');
    done.resolve();
  });

  limiter.write('a');
  limiter.write('b');
  // Write STOP on next tick to allow previous writes to flush
  process.nextTick(() => {
    limiter.write('STOP');
  });
  await done.promise;
});

// =============================================
// Error handling
// =============================================

tap.test('SmartDuplex: should emit error when writeFunction throws', async (tools) => {
  const stream = new SmartDuplex<string, string>({
    objectMode: true,
    writeFunction: async () => {
      throw new Error('write error');
    },
  });

  const done = tools.defer();
  stream.on('error', (err) => {
    expect(err.message).toEqual('write error');
    done.resolve();
  });

  stream.write('test');
  await done.promise;
});

tap.test('SmartDuplex: should error when no writeFunction and data is written', async (tools) => {
  const stream = new SmartDuplex<string, string>({
    objectMode: true,
  });

  const done = tools.defer();
  stream.on('error', (err) => {
    expect(err.message).toEqual('No stream function provided');
    done.resolve();
  });

  stream.write('test');
  await done.promise;
});

// =============================================
// fromWebReadableStream
// =============================================

tap.test('SmartDuplex: should create from a Web ReadableStream', async (tools) => {
  const chunks = ['hello', 'world', 'foo'];
  const webReadable = new ReadableStream<string>({
    start(controller) {
      for (const chunk of chunks) {
        controller.enqueue(chunk);
      }
      controller.close();
    }
  });

  const duplex = SmartDuplex.fromWebReadableStream(webReadable);
  const results: string[] = [];

  const done = tools.defer();
  duplex.on('data', (chunk: string) => results.push(chunk));
  duplex.on('end', () => {
    expect(results).toEqual(chunks);
    done.resolve();
  });
  await done.promise;
});

// =============================================
// getWebStreams
// =============================================

tap.test('SmartDuplex: should provide web streams via getWebStreams()', async () => {
  const duplex = new SmartDuplex<string, string>({
    objectMode: true,
    writeFunction: async (chunk) => {
      return chunk.toUpperCase();
    },
  });

  const { readable, writable } = await duplex.getWebStreams();

  const writer = writable.getWriter();
  const reader = readable.getReader();

  await writer.write('hello');
  await writer.write('world');
  await writer.close();

  const results: string[] = [];
  while (true) {
    const { value, done } = await reader.read();
    if (done) break;
    results.push(value);
  }

  expect(results).toContain('HELLO');
  expect(results).toContain('WORLD');
});

// =============================================
// Debug mode
// =============================================

tap.test('SmartDuplex: debug mode should not crash', async (tools) => {
  const stream = new SmartDuplex<string, string>({
    name: 'DebugStream',
    debug: true,
    objectMode: true,
    writeFunction: async (chunk) => chunk,
  });

  const done = tools.defer();
  stream.on('data', () => {});
  stream.on('end', () => done.resolve());

  stream.write('test');
  stream.end();
  await done.promise;
});

// =============================================
// Pipe with file read
// =============================================

tap.test('SmartDuplex: should handle a read stream pipeline', async () => {
  const streamWrapper = new smartstream.StreamWrapper([
    fs.createReadStream('./test/assets/readabletext.txt'),
    new smartstream.SmartDuplex({
      writeFunction: async (chunkStringArg: Buffer, streamTools) => {
        const result = chunkStringArg.toString().substr(0, 100);
        streamTools.push('wow =========== \n');
        return Buffer.from(result);
      },
      finalFunction: async () => {
        return Buffer.from('this is the end');
      },
    }),
    new smartstream.SmartDuplex({
      writeFunction: async (chunkStringArg) => {
        // consume data
      },
      finalFunction: async (streamTools) => {
        streamTools.push(null);
      },
    })
  ]);
  await streamWrapper.run();
});

export default tap.start();