## [Discuss] Using Black box to develop a test case for Tax calculator

Apply appropriate Black-box testing techniques to develop test cases for Tax Calculator application.
Tax Calculator is a program used to calculate taxes of incomes of citizens living in states: Alabama, Alaska, Arizona, California and Colorado.
Tax will be calculated based on the following formulas:
- Alabama, Alaska and Arizona have the same rate
If the income is equal to or smaller than \$10.000, tax will be 0 (zero).
If the income is larger than \$10.000 and smaller than \$35.000, tax will be calculated by the following formula: (the income – 10.000) x 5%. Otherwise, if the income is equal to or larger than \$35.000, tax will be equal to (the income – 15.000) x 7%.
However, if the person has got a family, tax will be:
[the income – 10.000 – (number of people in his/her family) x 4.000] x 5%
Or
[the income – 15.000 – (number of people in his/her family) x 4.000] x 7% if the income is equal to or larger than \$35.000.
For instance, a person who has income of \$19.000 and there are 2 people in his/her family, then his/her tax will be:
(19.000 – 10.000 – 2 x 4.000) x 5% = \$50

- California and Colorado have the same rate
If the income is equal to or smaller than \$15.000, tax will be 0 (zero).
If the income is larger than \$15.000 and smaller than \$43.000, tax will be calculated by the following formula: (the income – 15.000) x 8%.
Otherwise, if the income is equal to or larger than \$43.000, tax will be equal to (the income – 19.000) x 11%.
However, if the person has got a family, tax will be:
[the income – 15.000 – (number of people in his/her family) x 5.000] x 8%
Or
[the income – 19.000 – (number of people in his/her family) x 5.000] x 11% if the income is equal to or larger than \$43.000.
For instance, a person who has income of \$45.000 and is a single, then his/her tax will be:
(45.000 – 19.000) x 11% = \$2860
Note: if tax is smaller than 0, it will be rounded to 0.

GUI description:

Name Business Rules Default Value Attributes
Single - A radio button, selected when the person is single
- When selected, radio button “Family” and text field “number of people in the family” are disable
selected
- Required (if radio button “Family” is not selected)
Family - A radio button, selected when the person has got a family
- When selected, text field “number of people in the family” is enable
non-selected
- Required (if radio button “Single” is not selected)
Number of people in the family - A text field
- Max length = 2
- Value = positive integer only 1 - Required (if radio button “Family” is selected)
State - Combo box
- Value is one of the following states:
Alabama
Arizona
California