
The gauge should be initially empty (i.e., set to 0), and have a
  maximum value of 10 (although there's no indication of the maximum).

Click "+". The gauge should go up by one.

Click "-". It should go back down to zero.

Click "+" five times. The gauge should be at the halfway point.

Click "-" ten times. (Five type errors.)  Click "+" once. The gauge
 should be at one.

Click "+" twelve times. (Three mismatch errors.)  Click "-" once. The
 gauge should be at nine.

Click "-" four times. The gauge should be at the halfway point.

Click "Bigger". The range is now 11 instead of 10, so the gauge
 should be below halfway.

Click "Smaller". The range is back to 10, so the gauge should be at
 the halfway point.

Click "Smaller" five times. The range is now 5, so the gauge should
 be full.

Click "Smaller" once more. The range is now 4, so the gauge value
 should be 4 also.

Click "Bigger" and the gauge should be 80% full.

Click "Smaller" six times. (Two type errors.)  The minimum gauge range
 is 1, so click "Bigger" once and the gauge should be at halfway.

