Do I need to install coffee separately?

[laromand]

I have many years of client side javascript but nodejs is new to me.

I keep getting the following error when I run: npm test?

PS C:\DevProjects\jsonDiffProjects\json-diff-master> npm test

json-diff@0.9.0 test
coffee -c test; mocha test/*.js

'coffee' is not recognized as an internal or external command,
operable program or batch file.

[SlickNutter]

Although I have no experience with coffee script, I'd say so.
As you can see here coffee-script is called using coffee.