Restaurant365 Challenge Calculator

Summary

Task: Create a calculator that only supports an Add operation given a single formatted string

Implemented 8 requirements and 4 of 5 stretch goals, each as separate commits.

Code Structure

The solution contains the following projects:

• Calc: Main console application
• Contract: Library containing interface definitions and exceptions
• Calculator: Library containing calculator implementations
• Calculator.Tests: xUnit unit test suite

There are several ICalculator implementations in the Calculator library. I chose to keep several versions to demonstrate interface implementations and inheritance.

Each requirement listed below identifies the relevant implementation and tests.

Instructions

To run unit tests:

dotnet build
dotnet test

To run the console application:

cd Calc
dotnet build
dotnet run

Requirements

1. Support a maximum of 2 numbers using a comma delimiter. Throw an exception when more than 2 numbers are provided

• examples: 20 will return 20; 1,5000 will return 5001; 4,-3 will return 1
• empty input or missing numbers should be converted to 0
• invalid numbers should be converted to 0 e.g. 5,tytyt will return 5

Implementation Notes:

• Interface: Contract/ICalculator.cs
• Exceptions: Contract/Exceptions.cs
• Implementation: Calculator/SumTwoOperandsCalculator.cs
• Tests: Calculator.Tests/SumTwoOperandsTests.cs
• Console App: Calc/Program.cs

Additional notes:

• Interface includes subtraction, multiplication, and division. However, those operators are not implemented until later stretch goals.
• Various unit tests demonstrate calculations and TooManyOperandsCalculatorException

2. Remove the maximum constraint for numbers e.g. 1,2,3,4,5,6,7,8,9,10,11,12 will return 78

Implementation Notes:

• Interface: Unchanged
• Exceptions: Unchanged
• Implementation: Calculator/SumCalculator.cs added as base implementation, and modified SumTwoOperandsCalculator.cs to maintain old behavior
• Tests: Calculator.Tests/SumTests.cs added for new tests
• Console App: Calc/Program.cs updated in a second commit

3. Support a newline character as an alternative delimiter e.g. 1\n2,3 will return 6

Implementation Notes:

• Interface: Unchanged
• Exceptions: Unchanged
• Implementation: Calculator/SumCalculator.cs now includes the new delimiter. Old implementation (SumTwoOperandsTests.cs) overrides to maintain its behavior.
• Tests: Calculator.Tests/SumTests.cs includes additional unit tests
• Console App: Unchanged

4. Deny negative numbers by throwing an exception that includes all of the negative numbers provided

Implementation Notes:

• Interface: Unchanged
• Exceptions: Added "NegativeValuesCalculatorException" class
• Implementation: Calculator/SumCalculator.cs now checks for negative values, and throws exception
• Tests: Calculator.Tests/SumTests.cs includes additional unit tests
• Calc/Program.cs updated to handle new exception

5. Make any value greater than 1000 an invalid number e.g. 2,1001,6 will return 8

Implementation Notes:

• Interface: Unchanged
• Exceptions: Unchanged
• Implementation: Calculator/SumCalculator.cs now treats values > 1000 as 0. SumTwoOperandsTests.cs overrides this to maintain its old behavior.
• Tests: Calculator.Tests/SumTests.cs includes additional unit tests
• Console App: Unchanged

6. Support 1 custom delimiter of a single character using the format: //{delimiter}\n{numbers}

• examples: //#\n2#5 will return 7; //,\n2,ff,100 will return 102
• all previous formats should also be supported

Implementation Notes:

• Interface: Unchanged
• Exceptions: Added "InvalidExpressionCalculatorException" class
• Implementation: Calculator/SumCalculator.cs now uses RegEx to test for possible custom delimiters.
• Tests: Calculator.Tests/SumTests.cs includes additional unit tests
• Calc/Program.cs updated to handle exception

7. Support 1 custom delimiter of any length using the format: //[{delimiter}]\n{numbers}

• example: //[***]\n11***22***33 will return 66
• all previous formats should also be supported

Implementation Notes:

• Interface: Unchanged
• Exceptions: Unchanged
• Implementation: Calculator/SumCalculator.cs additional RegEx for new delimiter pattern
• Tests: Calculator.Tests/SumTests.cs includes additional unit tests
• Calc/Program.cs Unchanged

8. Support multiple delimiters of any length using the format: //[{delimiter1}][{delimiter2}]...\n{numbers}

• example: //[*][!!][r9r]\n11r9r22*hh*33!!44 will return 110
• all previous formats should also be supported

Implementation Notes:

• Interface: Unchanged
• Exceptions: Unchanged
• Implementation: Calculator/SumCalculator.cs updated RegEx to allow multiple custom delimiters
• Tests: Calculator.Tests/SumTests.cs includes additional unit tests
• Calc/Program.cs Unchanged

Stretch goals

1. Display the formula used to calculate the result e.g. 2,,4,rrrr,1001,6 will return 2+0+4+0+0+6 = 12

Implementation Notes:

• Interface: Added ICalculator2.cs as new interface to support formula without breaking old implementations
• Exceptions: Unchanged
• Implementation: Calculator/SumCalculator.cs now implements ICalculator2 and returns Tuple with the result and formula
• Tests: Calculator.Tests/SumTests.cs includes additional unit tests
• Calc/Program.cs Unchanged

2. Allow the application to process entered entries until Ctrl+C is used

Implementation Notes:

• Interface: Unchanged
• Exceptions: Unchanged
• Implementation: Unchanged
• Tests: Unchanged
• Calc/Program.cs now adds event handler for ConsoleCancelEventHandler, and executes calculator in while(true) loop

3. Allow the acceptance of arguments to define...

• alternate delimiter in step #3
• toggle whether to deny negative numbers in step #4
• upper bound in step #5

This stretch goal is not implemented. There are various libraries for parsing arguments, so I didn't feel a need to do it here.

4. Use DI

Implementation Notes:

• Interface: Unchanged
• Exceptions: Unchanged
• Implementation: Unchanged
• Tests: Unchanged
• Calc/Program.cs creates ServiceCollection and adds SumCalculator as the implementation to use for the ICalculator2 interface. CalcService now contains the main body of code, and ICalculator2 is injected

5. Support subtraction, multiplication, and division operations

Implementation Notes:

• Interface: Unchanged
• Exceptions: Unchanged
• Implementation: Calculator/Calculator.cs added as a more generic ICalculator2 implementation supporting Add, Subtract, Multiply, Divide. SumCalculator now inherits Calculator, while imposing restriction to use Add operator only.
• Tests: Calculator.Tests/CalculatorTests.cs added for testing new operators
• Calc/Program.cs now adds Calculator (instead of SumCalculator) as the ICalculator2 implementation to use. CalcService.cs now prompts user to enter an operator after entering the expression to calculate.