When God allowed Satan to tempt Job to leave Him by giving him trouble, that was one kind of test. Job was so righteous and upright in his life that God could boast about him to Satan (Job.1:8). Satan's argument was that it was God's provision and protection that placed Job in a comfortable place where he wasn't really being tempted. Satan suggested that God should allow him to trouble Job and then see Job getting upset with God and leaving him (vv.9-11). Of course, Job didn't sin even then.
The test was essentially trying to shake up an upright man and see if he would hold on to his faith under pressure. When our comfort zone is shaken up, when calamity hits us unexpectedly, when we think we are being treated unfairly by people or circumstances, when our suffering is not due to our own fault – that is one kind of test. Our tendency is to complain, and to find fault with God because we think life is not fair to us. Many people think, "I haven't done anything wrong. Why is this happening to me?" Philosophical questions come up in our mind, as with Job, concerning the presence of evil in this world and God's role as a perfect, almighty, loving Father. This kind of test is not easy to face because it doesn't make sense to us.
When we face such things in our life it comforts us to know stories like that of Job and what is going on in the heavenly places. This helps us to recognise that our Father in heaven is fully aware of what is going on, and that He is on our side. When the Devil accuses us, we have an Advocate on our side interceding for us. We can also get an experience of realising how small we are, and how little we really know. This will make the foundation of our faith stronger.
We see another type of test in the case of Peter. He was a zealous disciple of the Lord who was willing to stand with His Lord and even to die for Him, even if the others left Him (Mt.26:33;Jn.13:37). In his case, Jesus said that he was going to betray Him and yet hoped that he would not lose his faith (Lk.22:31,32). Peter fell, but kept his faith in the Lord because the Lord sustained him with an encouraging look (v.61).
If we fall as a believer, this is the kind of test we face with regard to our faith. We know in theory that there is forgiveness with God (1Jn.1:9), but we feel we are unworthy. We didn't want to sin, and, like Peter, we actually wanted to be most faithful to the Lord. This fall is difficult to take. It hurts our ego, brings us very low and causes us to want to hide from the Lord in shame (Ge.3:10).
But just as the fall helped Peter to have a more sober estimate about himself, we too can learn to think less about ourselves and lean more heavily on our Lord for our keeping (Jude.24,25). It helps us to clean out more facets of self-righteousness and pride that might be lurking inside us. It helps us to learn to watch and pray more earnestly (Mt.26:41). It also helps us to be compassionate towards the others.