TestComponent: Use is_empty instead of .len == 0

Signed-off-by: Maxime “pep” Buquet <pep@bouah.net>

src/component.rs

@@ -286,9 +286,8 @@ impl Drop for TestComponent {
         // while panicking" even when nobody asks for it (RUST_BACKTRACE unset). Let the error
         // appear if there isn't any other error.
         if !thread::panicking() {
-            assert_eq!(
-                self.expect_buffer.len(),
-                0,
+            assert!(
+                self.expect_buffer.is_empty(),
                 "Remaining expected elements in the buffer"
             );
         }