node-stream-helpers/test/filestream.test.ts

import * as assert from 'assert'
import { Source } from '../src/Source'
import * as Sink from '../src/Sink'
import * as fs from 'fs'

describe('file stream', function () {
  this.timeout(5000)

  it('should run a stream from a file', async () => {
    const value = await Source.fromReadableBuilder<Buffer>(() => fs.createReadStream('./resources/test/numbers.txt'))
      .map(v => v.toString('utf-8'))
      .map(numbers =>
        numbers
          .split(/\s+/)
          .filter(v => v.length > 0)
          .map(v => parseInt(v, 10))
          .reduce((a, b) => a + b, 0),
      )
      .into(Sink.sum)
      .run()

    assert.strictEqual(value, 525896510)
  })
})