Given: There is a calculator system. There is a screen input form consisting of 2 edit-boxes and a button - Calculate sum. When the button is pressed, another field appears showing the sum of the entered numbers. Task: Create a testing plan for this system. Condition - if the sum of numbers > 1000, the output field is colored green. If <= 1000, it is colored red.

Testing plan for the sum calculator with color indication:

1. Functional testing:

   • Enter two positive numbers, check the correctness of the sum.
   • Enter two negative numbers, check the sum.
   • Enter one positive and one negative number.
   • Enter zeros.
   • Verify that clicking the button displays the result field.

2. Boundary value testing:

   • Sum exactly 1000 (check the color of the field — should be red).
   • Sum slightly less than 1000 (e.g., 999).
   • Sum slightly more than 1000 (e.g., 1001) — the field should be green.

3. Input testing:

   • Enter non-numeric characters (letters, special symbols) — error handling check.
   • Empty fields — how the system reacts.
   • Very large numbers — check for overflow or errors.

4. UI testing:

   • Check the color of the output field depending on the sum (red or green).
   • Verify that the output field appears only after clicking the button.

5. Performance testing:

   • Rapid multiple clicks on the button — stability of operation.

6. Compatibility testing:

   • Check operation on different browsers/devices, if applicable.

7. Security testing:

   • Check for malicious data input (e.g., scripts).

This plan will cover the main usage scenarios and identify possible errors in logic and interface.