Jasmine's `andReturn` vs `andCallFake`

andReturn vs andCallFake

// Jasmine's `andReturn` sets the value at instantiation and it can 
// never be changed after that apparently. Use `andCallFake` instead 
// if you need it to be dynamic.


var value = 9;

var getValueOne = jasmine.createSpy('spyOneAndReturn').andReturn(value);

var getValueTwo = jasmine.createSpy('spyOneCallFake').andCallFake(function () {
  return value;
});

var setValue = jasmine.createSpy('spyTwo').andCallFake(function (newValue) {
  value = newValue;
});

getValueOne(); // 9
getValueTwo(); // 9
setValue(10);
getValueOne(); // still returns 9
getValueTwo(); // returns 10