The input is also known as data and is used to test the functional aspects of a product and this can be divided into three areas.
The first area which is concerned with normal testing is good data.
So if the manual dictates the setting of the time as the following sequence:
1. Press and hold the TIME button,
2. Press the HOUR button,
3. Press the MINUTE button.
4. Release the TIME button
Adhering to this process of setting the time would be classed as testing using good data.
The next two types of inputs are concerned with abnormal conditions.
These include the use of bad data, such as
1. Press and hold the HOUR button,
2. Press the MINUTE button,
3. Press the TIME button.
1. Press and hold the MINUTE button,
2. Press the TIME button,
3. Press the HOUR button.
As you can see there are several sequences in which the buttons TIME, HOUR and MINUTE can be used. Of which one sequence will correctly set the time. The other sequences can be classed as bad data because they are not in the correct order as specified by the instructions listed in the manual.
Absolutely, bad data could corrupt the alarm clock and cause it to fail.
The alarm clock is expecting data (that is input) to be entered in a specific way. It is not expecting bad data to be entered.
To overcome the issues of bad data the manufacturers of the alarm clock may alter the programming of their alarm clock. To ignore the pressing of buttons in different sequences to the one listed in the manufacturer's instructions.
So if the MINUTE button is pressed the alarm clock programming ignores this until it is pressed when the TIME button is being pressed and held. At this point the alarm clock program will accept input from the MINUTE button.