chai-interface

$ npm install chai-interface

    var chai = require('chai')
    chai.should()
    chai.use(require('chai-interface'))

    var foo = {
      bar: true,
      baz: 'green',
      qux: 37,
      quack: function () {},
      ducks: [1, 2, 3]
    }

    foo.should.have.interface({
      bar: Boolean,
      baz: String,
      qux: Number,
      quack: Function,
      ducks: Array
    })

    var user = {
      name: {
        first: 'Betty',
        last: 'Dodson'
      },
      emails: {
        work: 'b.dodson@megacorp.com',
        home: 'butterflychica947@lol.com',
        school: 'bdodso4@stateu.edu'
      }
    }

    user.should.have.interface({
      name: {
        first: String,
        last: String
      },
      emails: {
        work: String,
        home: String,
        school: String
      }
    })

Interface not as expected:
{
  "bars": {
    "actual": "Array<String>",
    "expected": "Array<Number>",
    "actualValue": [
      "a",
      "b",
      "c"
    ]
  }
}