anchor.diff:  
       // This test assumes that output from wiringPi pin 1 (BMC_GPIO 18, Phys 12)
       // can be read as input on wiringPi pin 0 (BMC_GPIO 17, Phys 11).
  -    test('digitalWrite and digitalRead', () async {
  +    test('digitalWrite and digitalRead', () {
         Pin sensorPin = gpio.pin(0, input)..pull = pullDown;
         Pin ledPin = gpio.pin(1, output)..value = 0;
  -      await _delay(1);
  -      expect(sensorPin.value, 0);
  +      _assertValue(sensorPin, 0);
         for (int count = 0; count < 3; ++count) {
           ledPin.value = 1;
  -        await _delay(1);
  -        expect(sensorPin.value, 1);
  +        _assertValue(sensorPin, 1);
           ledPin.value = 0;
  -        await _delay(1);
  -        expect(sensorPin.value, 0);
  +        _assertValue(sensorPin, 0);
         }
       });
   
  
positive.code:   int thresholdUp;
    for (int pulseWidth = 0; pulseWidth <= 1024; pulseWidth += 10) {
      ledPin.pulseWidth = pulseWidth;
      if (thresholdUp == null) await _delay(1);
      int value = sensorPin.value;
      if (thresholdUp == null && value == 1) thresholdUp = pulseWidth;
    }
  
negative.code:     test('pulseWidth and digitalRead - software pwm gpio.3', () async {
        Pin sensorPin = gpio.pin(2, input)..pull = pullDown;
        Pin ledPin = gpio.pin(3, pulsed)..pulseWidth = 0;
        _assertValue(sensorPin, 0);
  
        // Increase and note threshold at which pin 0 state changes
        int thresholdUp = await _pwmUp(ledPin, sensorPin);
  