Chai-Kekka

A Chai plugin for Kekka

Installation and Usage

Node: npm install --save-dev chai-kekka to get up and running.

const chai = require("chai")
const chaiKekka = require("chai-kekka")
 
chai.use(chaiKekka)

Documentation

Test value is a Type Result

The result property can be used to check that the tested value is an instance of the Result class.

expect(Success('Some String')).to.be.a.result
expect(Failure(new Error('Failure...'))).to.be.a.result

Test value is a Result Success

The success property can be used to check that the tested value is an instance of the Result class of type Success.

// Positive
expect(Success('Success String')).to.be.a.success // OK
expect(Failure(new Error('Failure...'))).to.be.a.success // FAIL
expect('Not a result').to.be.a.success // FAIL

// Negative
expect(Success('Success String')).not.to.be.a.success // FAIL
expect(Failure(new Error('Failure...'))).not.to.be.a.success // OK
expect('Not a result').not.to.be.a.success // FAIL with 'expected 'Not a result' to be an instance of Result'

Test value is a Result Failure

The failure property can be used to check that the tested value is an instance of the Result class of type Failure.

// Positive
expect(Success('Success String')).to.be.a.failure // FAIL
expect(Failure(new Error('Failure...'))).to.be.a.failure // OK
expect('Not a result').to.be.a.failure // FAIL

// Negative
expect(Success('Success String')).not.to.be.a.failure // OK
expect(Failure(new Error('Failure...'))).not.to.be.a.failure // FAIL
expect('Not a result').not.to.be.a.failure // FAIL with 'expected 'Not a result' to be an instance of Result'

Test associated value of a Result Object

There are two ways to test the associated value of a Result object:

  • the methods successWrapping and failureWrapping
  • the property associatedValue

successWrapping and failureWrapping

const error = new Error('Failure message')
expect(Failure(error)).to.be.a.failureWrapping(error) // OK
expect(Failure(error)).to.be.a.successWrapping(error) // FAIL - not a Success
expect(Failure(error)).to.be.a.failureWrapping('some other value') // FAIL

expect(Success('Success String')).to.be.a.successWrapping('Success String') // OK
expect(Success('Success String')).to.be.a.failureWrapping('Success String') // Fail - not a Failure

// equality modifiers can be used, such as deep, on successWrapping and failureWrapping
expect(Success({ a: '423' })).to.be.a.deep.successWrapping({ a: '423' })

associatedValue

The associatedValue property can be used after a result, success or failure property. It changes the target of any assertions that follow in the chain to be on the result associated value.

expect(Success('Success String')).to.be.a.success
  .with.associatedValue.that.equals('Success String') // OK
expect(Success({ a: '423' })).to.be.a.success
  .with.associatedValue.that.deep.equals({ a: '423' }) // OK - equality modifiers accepted
expect(Success({ a: '423' })).to.be.a.failure
  .with.associatedValue.that.deep.equals({ a: '423' }) // FAIL - not a failure
expect(Success({ a: '423' })).to.be.a.result
  .with.associatedValue.that.deep.equals({ a: '423' }) // OK
expect(Success('Success String')).to.have.associatedValue.that.equals('Success String') // FAILS 
// associatedValue must be after either a result, success or failure assertion property