text: const assert = require('assert')
  const CountStream = require('./countstream')
  const countStream = new CountStream('example')
  const fs = require('fs')
  let passed = 0
  
  countStream.on('total', count => {
    //<co id="callout-intro-countstream-test-1" />
    assert.equal(count, 1) //<co id="callout-intro-countstream-test-2" />
    passed++
  })
  
  fs.createReadStream(__filename).pipe(countStream) //<co id="callout-intro-countstream-test-3" />
  
  process.on('exit', () => {
    //<co id="callout-intro-countstream-test-4" />
    console.log('Assertions passed:', passed)
  })
  