Assertions on results of method execution

It would be nice if there would be assertions that let you execute a js on the page and asserts the return value with a value to check if the js works correctly.

[asciidisco]

There is some kind of experimental API, that does this (kind of):

.execute(function () {
  var time = new Date(window.commentTimestamp);
  this.assert.ok((time.getMonth() === 2), 'Month has been set correct in the timestamp');
})

It only supports the .ok() assertion for now, which just checks if the given value is truthyor not.