assert(val)
assert.fail(actual, expected)
assert.ok(val) // is truthy
assert.equal(actual, expected) // 'compare with =='
assert.strictEqual
assert.deepEqual

assert.isTrue
assert.isFalse

assert.isNull
assert.isNotNull
assert.isUndefined
assert.isDefined
assert.isFunction
assert.isObject
assert.isArray
assert.isString
assert.isNumber
assert.isBoolean

assert.typeOf(/tea/, 'regexp') // Object.prototype.toString()
assert.instanceOf(chai, Tea)
assert.include([ a,b,c ], a)
assert.match(val, /regexp/)
assert.property(obj, 'tea') // 'tea' in object
assert.deepProperty(obj, 'tea.green')
assert.propertyVal(person, 'name', 'John')
assert.deepPropertyVal(post, 'author.name', 'John')

assert.lengthOf(object, 3)
assert.throws(function() { ... })
assert.throws(function() { ... }, /reference error/)
assert.doesNotThrow

assert.operator(1, '<', 2)
assert.closeTo(actual, expected)

.to .be .been .is .that .and .have .with .at .of .same

expect(object).not.equal('x')

expect(object)
  .equal(expected)
  .eql
  .deep.equal(expected) // same as .eql
  .be.a('string')
  .include(val)

  .be.ok(val)
  .be.true
  .be.false

  .be.null
  .be.undefined
  .be.empty
  .be.arguments
  .be.function
  .be.instanceOf

  .gt(5)  # or .above .greaterThan
  .gte    # or .at.least
  .lt(5)  # or .below

  .respondTo('bar')
  .satisfy (n) -> n > 0

  .have.members([2, 3, 4])
  .have.keys(['foo'])
  .have.key('foo')

  .exist

expect(-> ...)
  .throw /not a function/

    global.jQuery = ...;
    chai.use(require('chai-jquery'));

    expect($body)

      .have.attr('foo')
      .have.prop('disabled')
      .have.css('background')
      .have.css('background-color', '#ffffff')
      .have.data('foo')

      .have.class('active')
      .have.id('id')

      .have.html('<em>hi</em>')
      .have.text('hello')
      .have.value('2013')

      .be.visible
      .be.hidden

      .be.checked
      .be.selected

      .be.enabled
      .be.disabled

      .be.empty
      .to.exist
      .to.contain('text')
      .to.have('.selector')