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The Calculator program allows users to perform basic arithmetic operations from the command line. The invocation syntax is as follows:
java Calculator COMMAND ARG_1 ARG_2 [ARG_3] ... [ARG_N]
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FEATURES
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Addition
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Feature: The program can be used to provide the sum of an arbitrary number of operands. The command for performing addition is “--add”.
Scenario: Add two numbers together
Given the command: --add
And the arguments: 3 1.5
When Calculator is executed
Then “3.0 + 1.5 = 4.5” is displayed
Scenario: Add more than two numbers together
Given the command: --add
And the arguments: 1.75 2 3.0 4 5.25
When Calculator is executed
Then “1.75 + 2.0 + 3.0 + 4.0 + 5.25 = 16.0” is displayed
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Subtraction
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Feature: The program can be used to provide the difference between two numbers. The command for performing subtraction is “--sub”.
Scenario: Find the difference between two numbers
Given the command: --sub
And the arguments: 3 1.5
When Calculator is executed
Then “3.0 − 1.5 = 1.5” is displayed
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Multiplication
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Feature: The program can be used to provide the product of an arbitrary number of operands. The command for performing addition is “--mult”.
Scenario: Multiply two numbers together
Given the command: --mult
And the arguments: 5 1.5
When Calculator is executed
Then “5.0 × 1.5 = 7.5” is displayed
Scenario: Multiply more than two numbers together
Given the command: --mult
And the arguments: 1.5 2 3.25
When Calculator is executed
Then “1.5 × 2 × 3.25 = 9.75” is displayed
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Division
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Feature: The program can be used to provide the quotient of two numbers. The command for performing division is “--div”.
Scenario: Find the quotient of two numbers
Given the command: --sub
And the arguments: 3 2.0
When Calculator is executed
Then “3.0 ÷ 2.0 = 1.5” is displayed
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Exponentiation
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Feature: The program can be used to provide the value of a base number raised by an exponent. The command for performing exponentiation is “--pow”.
Scenario: Raise a base number by an exponent
Given the command: --pow
And the arguments: 3 2
When Calculator is executed
Then “3 raised to the power of 2 = 9” is displayed
Scenario: Fractional exponents are not allowed
Given the command: --pow
And the arguments: 3 2.5
When Calculator is executed
Then “Error: Fractional exponents are not allowed” is displayed as an error
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Error Reporting
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Feature: In order to make the program more user friendly, helpful feedback is provided when the user provides invalid input.
Scenario: An invalid number of arguments is provided for a command
Given the command: <Command>
And the invalid arguments: <Arguments>
When Calculator is executed
Then <Message> is displayed as an error
Examples:
| Command | Arguments | Message |
| --add | 1 | Usage: Calculator --add addend_1 addend_2 [addend_3] ... [addend_n] |
| --sub | 1 2 3 | Usage: Calculator --sub minuend subtrahend |
| --mult | 7 | Usage: Calculator --mult factor_1 factor_2 [factor_3] ... [factor_N] |
| --div | | Usage: Calculator --div dividend divisor |
| --pow | 4 5 6 | Usage: Calculator --pow base exponent |