it('should invoke registered commands and execute one that can handle the request', () => {
let chain = new CommandChain();
let result = chain.add(new Command1()).add(new Command2()).execute('string');
expect(result).to.equal('string=string');
result = chain.execute(true);
expect(result).to.equal('boolean=true');
});
expect(() => {
let chain = new CommandChain();
chain.add(new Command1()).execute(true);
}).to.throw(Error);