'Tester' in the Bible

A crucible for silver, and a smelter for gold,and the Lord is the tester of hearts.

Every way of a man seems right to himself, but the Lord is the tester of hearts.

If you say, See, we had no knowledge of this: does not the tester of hearts give thought to it? and he who keeps your soul, has he no knowledge of it? and will he not give to every man the reward of his work?