Sinon: Document how to stub getters and setters

[fatso83]

PR #692 introduced the feature of stubbing getters and setters. This is as of yet undocumented. Some of the comments show examples of how to make use of this feature.

[mroderick]

@fatso83 do you think that #1182 adequately solved this issue? Can we close it?

[bdentino]

With the introduction of callsFake, the documented way of stubbing getters/setters logs a warning:

sinon.stub(obj, 'meth', fn) is deprecated and will be removed fromthe public API in a future version of sinon.
 Use stub(obj, 'meth').callsFake(fn).
 Codemod available at https://github.com/hurrymaplelad/sinon-codemod

Is this feature still supported?

[fatso83]

Yes, but using a different syntax. See the get and set methods at the bottom of http://sinonjs.org/releases/v2.0.0/stubs/. Closing this.

[bdentino]

Perfect. Thanks for the quick response!

[derwaldgeist]

The new syntax is awesome. But it doesn't tell how a stubbed getter would be restored?

[fatso83]

@derwaldgeist Oh, but it does. As I mentioned above, just see the bottom of the page: http://sinonjs.org/releases/v2.3.1/stubs/

P.S. If you feel the docs could be improved, please feel free to push a PR. The docs are in this repo.

A working example

// test.js 
var sinon = require('sinon');

console.log('#getter-stub example')
var obj = { 'foo' : 'foo-val' }
console.log(obj.foo);

var stub = sinon.stub(obj, 'foo').get( () => 'fake-val' );

console.log(obj.foo);
// this won't work as obj.foo returns a value, not the stub 
// - might be possible to improve the API here!
// obj.foo.restore(); 
stub.restore();
console.log(obj.foo);

console.log('\n#value-stub example')

var stub2 = sinon.stub(obj, 'foo').value( 'new-fake-val' );
console.log(obj.foo);

// this won't work for the above reasons
// => TypeError: obj.foo.restore is not a function
// obj.foo.restore();
stub2.restore();
console.log(obj.foo);

Output

$ node test
#getter-stub example
foo-val
fake-val
foo-val

#value-stub example
new-fake-val
foo-val

[derwaldgeist]

@fatso83: @fatso83: It was my fault. I tried to stub the getter of an instance of the class. This worked, but the restore() reported Cannot redefine property: <name of the getter>. I now stubbed the getter on the prototype of the class, this works. Thanks for your help.

[hovissimo]

If you're reading this from a google search you want to read https://sinonjs.org/releases/latest/stubs/ instead!