Add missing tests in test_bytes

tests/test_bytes.rs

@@ -157,6 +157,13 @@ fn slice_oob_2() {
     a.slice(44..49);
 }
 
+#[test]
+#[should_panic]
+fn slice_start_greater_than_end() {
+    let a = Bytes::from(&b"hello world"[..]);
+    a.slice(5..3);
+}
+
 #[test]
 fn split_off() {
     let mut hello = Bytes::from(&b"helloworld"[..]);
@@ -724,6 +731,15 @@ fn advance_past_len() {
     a.advance(20);
 }
 
+#[test]
+#[should_panic]
+fn mut_advance_past_len() {
+    let mut a = BytesMut::from("hello world");
+    unsafe {
+        a.advance_mut(20);
+    }
+}
+
 #[test]
 // Only run these tests on little endian systems. CI uses qemu for testing
 // big endian... and qemu doesn't really support threading all that well.