sarahfrench / conwaygameoflife

An implementation of Conway's Game of Life using TDD.

Conway's Game Of Life

Brief & Details

Task:

Implement Conway's Game of Life using TDD, to satisfy tests based on the scenarios listed below.

Links:

• My notes during this project
• Code from this repo made into a small Vue app that visualises the game
  • I've recently started learning Vue and thought this would be fun!
  • The code will need refactoring once I know more about Vue
• Deployment of the above Vue app

Assumptions made:

It's assumed that a new instance of the GameOfLife class is made by passing in an array of arrays, containing 1's or 0's to indicate life and death:

let board = [
  [0,0,0],
  [1,1,1],
  [0,0,0]
]
let game = GameOfLife.new(board);

There are some checks to make sure the input is sensible, but it's assumed the values inside are either 0 or 1.

Not infinite : My solution isn't infinite as the brief describes, but can take in starting states of different sizes.

The edges of the board are solid boundaries: The grid doesn't wrap around (similar to a game of Snake, or Pac-Man). This could probably be added by using a modulo to calculate coordinates of neighbours on the other side of the board.

This change would allow the simulation to sustain itself much longer, as the boundaries reduce the number of possible neighbours and inhibit life.

Cloning this project

Clone this repository and run npm install.

Tests:

Mocha is used to run tests for different scenarios (see below). Use the command npm run test to run all the tests.

• npm run scenario : runs just integration tests from the brief (test/scenarios.js)
• npm run unit : runs just unit tests for the GameOfLife class (test/unit-tests.js)

The above should work for using the local mocha files, but if there are issues with mocha install it globally using npm i --global mocha and then run mocha in the project's root.

Scenarios

Use these for test driven development

Scenario 0 No interactions

Given a game of life

When there are no live cells

Then on the next step there are still no live cells

Scenario 1: Underpopulation

Given a game of life

When a live cell has fewer than two neighbours

Then this cell dies

Scenario 2: Overcrowding

Given a game of life

When a live cell has more than three neighbours

Then this cell dies

Scenario 3: Survival

Given a game of life

When a live cell has two or three neighbours

Then this cell stays alive

Scenario 4: Creation of Life

Given a game of life

When an empty position has exactly three neighbouring cells

Then a cell is created in this position

When applied these scenarios result in the following:

Scenario 5: Grid with no live cells

Given a game of life with the initial state containing no live cells

When the game evolves one turn

Then the next state also contains no live cells

Scenario 6: Expected game outcome for seeded grid

Given a game of life with the initial state...

+---+---+---+
| O | O | O |
| X | X | X |
| O | O | O |
+---+---+---+

When the game evolves one turn

Then the next state is...

+---+---+---+
| O | X | O |
| O | X | O |
| O | X | O |
+---+---+---+

When the game evolves another turn

Then the next state is...

+---+---+---+
| O | O | O |
| X | X | X |
| O | O | O |
+---+---+---+