Isaiah 38

It took less than 5 minutes to read this.chapter. Shortly after God saved Jerusalem from the king of Ashur, and apparently before the king was killed as Isaiah predicted, king Hezekiah became ill. In the midst of this potential threat by the king of Ashur and Hezekiah's illness the prophet came to the king and passed on God message: "You will not recover. You will die from this disease." I wonder why God put Hezekiah through this test. I suppose that the king passed the test, because God reversed his death sentence, and granted him 15 years. But I wonder: did Hezekiah get his house in order within the next 15 yaers?
Stuart