Calculator with GUI

Simple Calculator with a GUI using Python and PySimpleGui 4.60.5

Goal: GUI, calculations and call functions in order (PEMDAS), Unittests

This is a task of the book “Exercises for Programmers - 557 Challenges to Develop Your Coding Skills” by Brian P. Hogan. This book focuses on giving tasks and not solutions.

Task

Create a Calculator WITHOUT using eval() on the input

Input

• GUI input
  • numbers
  • operations
    • Addition (+)
    • Subtraction (-)
    • Multiplication (*)
    • Division (/)
    • Exponentiation
      • potentiation (**)
      • square root (sqrt())
      • cubic root (**(1./3.))
      • x root (**(1./x.))
  • minus sign (-)
  • float point
  • compute (=)

Conversions

• check if calculation is possible (division by 0)
• calculate

Output

• result
• Feedback when division is not possible

Psuedo code

TipCalculator
    Initialize calculator
    Initialize GUI
        buttons
        text-field

    Repeat
        Get input
        Update text-field
    
    On calculate
        Split field input to numbers and operations
        Convert numbers to numbers (float)
        Calculate operations in order while checking if operations are possible
    
    Feedback-Pop-Up on error if there is an error
    Display result
End

Project Structure

.
├── .gitignore
├── readme.md
├── requirements.txt
├── simple_gui.py
├── calculator
│   ├── __init__.py
│   └── calculator.py
└── tests/
    ├── __init__.py
    └── test_calculator.py

Tests

• Operations (as float)
  • Addition (+)
  • Subtraction (-)
  • Multiplication (*)
  • Division (/)
  • Exponentiation
    • potentiation (x**y)
    • consecutive potentiation (x**y**z)
    • square root (sqrt(x))
    • cubic root (x**(1/3))
    • xth root (y**(1/x))
• Division by 0
• Operations hierarchy (PEMDAS¹)
  • Parentheses, Exponentiation, Multiplication/Division, Addition/Subtraction from left to right.
• Input-string validation

Assertion-Test: Operations (as float)

Test-Plan: Addition (+)

Inputs:
  123.45 + 670.89
Expected result:
  794.34

Test-Plan: Substraction (-)

Inputs:
  670.89 - 123.45
Expected result:
  547.44

Test-Plan: Multiplication (*)

Inputs:
    123.45 * 670.89
Expected result:
  82821.3705

Test-Plan: Division (/)

Inputs:
  123.45 / 670.89
Expected result:
  0.18400930107767294

Test-Plan: Exponentiation, potentiate (x**y)

Inputs:
  2 ** 2
  2 ** 3
  2 ** 4
  2 ** 5
  2 ** 6
  2 ** 7
  2 ** 8
  2 ** 9
Expected result:
  4
  8
  16
  32
  64
  128
  256
  512

Test-Plan: Exponentiation, consecutive potentiation (x**y**z)

Inputs:
  2 ** 2 ** 2
Expected result:
  16

Test-Plan: Exponentiation, square root (sqrt(x))

Inputs:
  123.4567809 ** (1/2)
Expected result:
  11.111110696055547

Test-Plan: Exponentiation, qubic root (x**(1/3))

Inputs:
  123.4567809 ** (1/3)
Expected result:
  4.979338483283606

Test-Plan: Exponentiation, xth root (y**(1/x))

Inputs:
  123.4567809 ** (1/4)
  123.4567809 ** (1/5)
  123.4567809 ** (1/6)
  123.4567809 ** (1/7)
  123.4567809 ** (1/8)
  123.4567809 ** (1/9)
Expected result:
  3.333333271074998
  2.620010246173881
  2.2314431391553775
  1.9897011447521342
  1.8257418413004063
  1.7076173150528808

Assertion-Test: Division by 0

Test-Plan:

Inputs:
  10 / 0 
Expected result:
  ZeroDivisionError

Assertion-Test: Operations hierarchy (PEMDAS)

Test-Plan:

Inputs:
  10 + 15 * (3 - 8) ** 5
Expected result:
  -46865

Assertion-Test: Input-string validation

Test-Plan:

Inputs:
  10+0.23023--100*(15-5)**2
  10/15a
  10/0
  10+0.23023--100*15-5)**2
  10+0.23023(100*15-5)**2
Expected result:
  True
  Type = str
  Type = str
  Type = str
  Type = str

Additional, optional Tasks

• Add brackets/parentheses functionality
• Add scientific calculations
• Display thousand-separator on input “1,000,000.00”