It is said in Yoga Sutra 2.35 that when a person has mastered ahimsa, and so has an absence of the inclination to harm anyone, that those who come into his or her presence will experience a natural loss of hostility. In other words, if you've mastered ahimsa and an angry person comes into your presence, his or her anger vanishes. This can be a test for whether someone has mastered Ahimsa.
I've actually experienced this. One time, I became very angry at my meditation teacher, Swami Veda Bharati. So, I went to him and said, "Swamiji! I'm angry at you!"
He immediately put his arm around my shoulders and said, "Let's walk; please tell me about your anger."
Then he added, "It's okay that you're angry; I don't get angry back."
As we were walking, I felt his arm around my back and his kind, gentle, lovingness. My anger vanished. I was not able to feel it anymore, but I was determined to tell him why I was angry. I managed to say what he did that I didn't like, but I was not able to feel or express the anger, as it no longer existed.
Such is the effect of one who has mastered non-violence.