Why does Odysseus want to test his servants and his wife before revealing his identity in book 17?
Odysseus has been gone for twenty years, and the gods disguise him because he needs to know which of the suitors are evil and if any of them are still men of character who will leave when they realize Odysseus is still alive. Odysseus must test the suitors, therefore. Because of his long absence, it would also be unwise of Odysseus to just show up as himself. Penelope would probably have a heart attack, although she has never given up some hope that Odysseus is still alive. Odysseus also needs to see which of his servants have turned against him and have allied themselves with certain of the suitors. Odysseus gains an advantage over the suitors through his disguise, learning which suitors he should deal with first. Antinoos distinguishes himself right away when he throws the footstool at Odysseus, and the other suitors even tell him he's out of line, for the beggar could be a god disguised as a beggar. They know how some of the Greek gods and goddesses liked to mingle with the people on earth, especially Zeus, who often disguised himself to be with women on earth.
Having spoken with Agamemnon in the underworld (Book 11), Odysseus is warned not to trust his wife entirely. Agamemnon's wife conspired to kill him and accomplished this when he returned from Troy.
Odysseus want to assess who has been loyal to him so that he may have his just revenge for all those who spoiled his house and took advantage of his absence.
The old Odysseus would have immediately resorted to using brawn, but this Odysseus has learned to control his "fighting spirit"
because odysseus is the only person that can string a bow and shoot it threw 12 axe holes. Odysseus and Telemachus
Odysseus has been away from home over twenty years. When he finally reaches the shores of Ithaca, he is stopped from entering his home by Athena. There is no joyous reunion, instead finds that his home has been overwhelmed by the greedy suitors who have corrupted some of his servants. The test of the servants is only nature. He has to know how far the corruption has gone.
As for the test of Penelope, a wife who has been on her own for twenty years, Odysseus maybe suspicious that like himself, she found companionship during those years. Remember also that the test goes both ways, Penelope tests Odysseus to make sure that it is really him. She does this when she asks him the question about their bed.