Caffeine provides a few handy tools that are present in most OO languages, exposed through a commonjs module. Its niceties are optimized for CoffeeScript.

caff = require "caffeine"

Exceptions

Caffeine provides the extensible Exception class that captures stack trace and succeeeds in instancesof inheritance checks in most browsers.

class MyException extends caff.Exception

try
    throw new MyException "some message"
catch e
    console.log e instanceof Error        # 'true'
    console.log e instanceof Exception    # 'true'
    console.log e instanceof MyException  # 'true'

Assumptions

Programming errors can lead to precondition violations when executing functions, resulting in hard-to-find bugs. Caffeine provides a simple API for validating preconditions at runtime, allowing the developer to surface these bugs early.

You can append an execption message to use, should the assumption fail.

assume = caff.Assume
assume true, "I should not throw"           # okay
assume false, "I expected a true value"     # throws caff.AssumptionException

assume.Exists var                   # throws if 'var' is undefined or null
assume.Equal a, b                   # throws if a != b

Numbers

Some simple checks are implented for numbers.

• Num.IsFloat
• Num.IsInt
• Num.IsEven
• Num.IsOdd

Unit Testing

Simple unit tests are easy to write as well, and Assertions work similarly to Assumptions.

class MyTest extends caff.TestSuite
    TestSomething: () ->
        @Assert true
        @Assert false, "some message"    # I'll throw a caff.TestException

        bad = () -> throw new MyException "boo!"
        good = () -> console.log "I have a halo"

        @AssertThrows MyException, bad            # This will pass just fine
        @AssertThrows MyException, good           # This will fail

new MyTest().Run()  # outputs results to console