Certain

Certain is a simple assertion library.

Install:

$ npm install certain

Usage is pretty simple:

var certain = require('certain')

certain('a').equals('a')

certain(false).is.true() // this will throw an AssertionError

API

certain(actual)

main certain method is called with the actual value then there are chained methods which allow the actual value to be compared to the corresponding expected value.

If the assertion is not correct certain will throw an AssertionError (this means you can use your preferred test suite provided that it fails the test on error)

There are also a number of chained properties which are available to improve semantics for test readability these are:be, to, does, is

For each of the below assertion methods it is possible to invert the assertion type by using: not, doesnt for example: certain('a').does.not.equal('b')

#equals(expected, msg) & #not.equal(expected, msg)

Assert that actual value triple equals to the expected value

certain('a').equals('a')

certain('a').equals('b') // will throw AssertionError

certain('a').does.not.equal('b')

certain('a').does.not.equal('a') // will throw AssertionError

certain('a').does.notEqual('b')

certain('a').does.notEqual('a') // will throw AssertionError

#deepEquals(expected, msg) & #not.deepEqual(expected, msg)

Assert that the actual value deepEquals to expected (this checks the values of properties of a specified object rather than references)

certain({ a: 1 }).deepEquals({ a: 1 })

certain({ a: 1 }).deepEquals({ a: 2, b: 3 }) // will throw AssertionError

certain({ a: 1 }).does.not.deepEqual({ a: 2, b: 3 })

certain({ a: 1 }).does.not.deepEqual({ a: 1 }) // will throw AssertionError

certain({ a: 1 }).does.notDeepEqual({ a: 2, b: 3 })

certain({ a: 1 }).does.notEqls({ a: 1 }) // will throw AssertionError

#is.true( msg) & #is.not.true(msg)

Assert that actual value is or is not equal to true

certain(true).is.true('It is true!')

certain(false).is.true() // will throw AssertionError

certain(false).is.not.true()

certain(true).is.not.true() // will throw AssertionError

#is.false(msg) & #is.not.false(msg)

Assert that actual value is or is not equal to false

certain(false).is.false('It is false!')

certain(true).is.false() // will throw AssertionError

certain(true).is.not.false()

certain(false).is.not.false() // will throw AssertionError

#is.ok(msg) & #is.not.ok(msg)

Assert that actual value is truthy by checking: Boolean(expected)

certain(1).is.ok('It is OK!')

certain(0).is.ok() // will throw AssertionError

certain(false).is.not.ok()
certain(null).is.not.ok()
certain(undefined).is.not.ok()

certain(true).is.not.ok() // will throw AssertionError

#throws(msg) & #does.not.throw(msg)

This expects that the actual value passed is a function and will assert if this function throws an error when called

certain(function () {
  throw new Error()
}).throws()

certain(function () {
  return true
}).throws() // will throw AssertionError

certain(function () {
  return false
}).doesnt.throw()

certain(function () {
  throw new Error()
}).does.not.throw() // will throw AssertionError