chai-generator

This is a plugin for chai to simplify the testing of Javascript generators, as introduced in ES6 / ES2015.

Because the yield / return signature of generators is a little obtuse, it can result in annoyingly verbose tests:

expect(generator.next()).to.deep.equal({ done: false, value: 15 })
expect(generator.next()).to.deep.equal({ done: true, value: -1 })

chai-generator removes the muck so your test can look like your intent:

expect(generator).to.yield(15)
expect(generator).to.return(-1)

Setup

node.js / io.js

var chai = require('chai')
chai.use(require('chai-generator'))

Browser

<script src="chai.js"></script>
<script src="chai-generator.js"></script>

Assertions

.yield

Assert that a value is yielded from generator.next(). Returned values are not considered yielded.

expect(generator).to.yield()
expect(generator).to.yield(1)
expect(generator).not.to.yield('missing')
expect(generator.next(10)).to.yield(10)

generator.should.yield()
generator.should.yield(1)
generator.should.not.yield('missing')
generator.next(10).should.yield(10)

assert.yield(generator, 1)
assert.notYield(generator, 'missing')
assert.yield(generator.next(10), 10)

.yield works with the .deep chain:

expect(generator).to.deep.yield([1, 2, 3])
generator.should.deep.yield([1, 2, 3])
assert.deepYield([1, 2, 3])

.yield can also be chained with other assertions (not available with assert):

expect(generator).to.yield().and.equal(1)
generator.should.yield().and.equal(1)

.return

Assert that a value is returned from generator.next(). Yielded values are not considered returned.

expect(generator).to.return()
expect(generator).to.return(1)
expect(generator).not.to.return('missing')
expect(generator.next(10)).to.return(10)

generator.should.return()
generator.should.return(1)
generator.should.not.return('missing')
generator.next(10).should.return(10)

assert.return(generator)
assert.return(generator, 1)
assert.notReturn(generator, 'missing')
assert.return(generator.next(10), 10)

.return works with the .deep chain:

expect(generator).to.deep.return([1, 2, 3])
generator.should.deep.return([1, 2, 3])
assert.deepReturn([1, 2, 3])

.return can also be chained with other assertions (not available with assert):

expect(generator).to.return().and.equal(1)
generator.should.return().and.equal(1)

License

chai-generator is released under the MIT License