mock/spy/stub module

[legendecas]

Is your feature request related to a problem? Please describe.
Provides a mock/spy/stub module natively in yodart.

Describe the solution you'd like

var esp = require('@yodaos/espionage')

var target = {
  tweet: () => { 
    return 'foobar'
  }
}
var spy = esp.spy(target, 'foo')
target.tweet('foo', 'bar')
spy.calledWith('foo', 'bar')
spy.returned('foobar')

[yorkie]

How about integrating sinonjs instead of re-implementing it? And sinon supports fake timers which could be used in testing with our alarm/reminder.

[yorkie]

Ping @yodaos-project/js