stubbing.js

it( "should build a greeting based on age", function() {
    var ds = new DataService();

    sinon.stub( ds, "getMessageBasedOnAge" )
      .withArgs( 20 )
      .returns( "Yo" );

    var g = new Greeting1( ds );

    var message = g.build( "Joe", 20 );

    assert.equal( message, "Yo, Joe!" );
  } );