Beautiful assertions for CoffeeScript. See the test file for examples.

Looks like this:

expect(a) to equal b

expect(c) to exist

expect(d) to nt equal e

expect([]) to have length 0

This assertion DSL is designed to take advantage of CoffeeScript's largely parenthesis-free syntax. Don't use it with plain JS unless you want assertions that look like this

expect({})(to(nt(be(an(Array)))));

In many cases CoffeeScript's terse syntax is especially great for writing unit tests, since there tends to be lots of boilerplate and repeated code, and tons of it and describe blocks to close. Even for projects written in regular JS, testing with CoffeeScript is excellent. While not as full-featured as libraries like Chai, sentence provides a basic set of assertions that will cover most use cases.

Admittedly, I've focused on keeping the code itself as pretty as possible. A number of features are infeasible with the current approach.

expect(1) to equal 1

Assert that two values are equal.

expect(a: "b", c: "d") to eql a: "b", c: "d"

Assert that two values are deeply equal. Uses the deep-equal package, with the strict option enabled.

expect(2) to be greater than 1

Assert that a value is greater than another value.

expect(1) to be less than 2

Assert that a value is less than another value

expect("hello there") to contain "hello"

Assert that one value contains another value (using indexOf). Supports strings and arrays.

expect(name: "Nick") to have("name") "Nick"

Assert that an object has a property equal to a value.

expect("hello there") to match /hello/

Assert that a string satisfies a regular expression.

expect([]) to be an Array
expect("") to be a String
expect(true) to be an Object # fails

Assert that an object is an instance of a constructor. Doing expect(x) to nt be an Object tests if x is a primitive value (i.e. string, number, boolean, symbol)

expect(0) to exist

Assert that a value is not null or undefined

expect({}) to be empty

Assert that an object has no own enumerable keys, or if an array that it's length is zero.

expect(1) to be ok

Assert that a value is truthy

expect(-> throw new Error) to error

Assert that a function throws an error when called

expect([1,2,3]) to have length 3

Special function for "has" in the common case of checking an object's length

# these all pass
expect(false) to nt be ok
expect(null) to nt exist
expect([1]) to nt be empty
expect({}) to nt be an Array
expect([1]) to nt have length 2
expect([]) to nt contain 1
expect(->) to nt error
expect("a") to nt match /b/
expect(x: "y") to nt have("x") "z"

Reverse an assertion chain