Install NodeJS
Install Git
Type these commands (each line as a seperate command) in the command line:

npm install -g mocha
git clone https://github.com/nles/tdd_example.git
cd tdd_example
npm install

Install Homebrew
Type these commands (each line as a seperate command) in the terminal (Terminal.app for example):

brew install node
sudo npm install -g mocha
git clone https://github.com/nles/tdd_example.git
cd tdd_example
npm install

In the tdd_example directory, run the following in command line or terminal:

mocha

If the command above fails, try the following:

./node_modules/mocha/bin/mocha