test(framework): change iterator exception asserts

change RocksDB iterator exception checks to use Assert.assertThrows for clearer intent and stricter failure behavior when expected exceptions are not thrown.

Author: bladehan1

framework/src/test/java/org/tron/core/db/DBIteratorTest.java

@@ -95,11 +95,7 @@ public void testRocksDb() throws RocksDBException, IOException {
         Assert.assertArrayEquals("2".getBytes(StandardCharsets.UTF_8), iterator.next().getKey());
         Assert.assertFalse(iterator.hasNext());
 
-        try {
-          iterator.seekToLast();
-        } catch (Exception e) {
-          Assert.assertTrue(e instanceof IllegalStateException);
-        }
+        Assert.assertThrows(IllegalStateException.class, iterator::seekToLast);
       }
       try (
           RockStoreIterator iterator =
@@ -112,16 +108,8 @@ public void testRocksDb() throws RocksDBException, IOException {
           iterator.next();
         }
         Assert.assertFalse(iterator.hasNext());
-        try {
-          iterator.getKey();
-        } catch (Exception e) {
-          Assert.assertTrue(e instanceof IllegalStateException);
-        }
-        try {
-          iterator.getValue();
-        } catch (Exception e) {
-          Assert.assertTrue(e instanceof IllegalStateException);
-        }
+        Assert.assertThrows(IllegalStateException.class, iterator::getKey);
+        Assert.assertThrows(IllegalStateException.class, iterator::getValue);
         thrown.expect(NoSuchElementException.class);
         iterator.next();
       }