Did Jesus not know whether or not He was ready to perform miracles? I'm sure He did! We know that: "Even if we feel guilty, God is greater than our feelings, and he knows everything." (1 John 3:20, NLT) So why this particular dialogue? I'm not so sure that it's to test Jesus' readiness but perhaps humanity's acknowledgement of Who He is. Did He lie about His hour not yet having come? Not likely. His hour may have arrived at that very next moment when she speaks to the servants in faith. Time is a very different concept for God than it is for us.