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