Cover metadata-only Debug output

src/tests.rs

@@ -61,6 +61,37 @@ fn assert_guard_state<T>(guard: &ContentGuard<'_, T>, expected_len: usize) {
     );
 }
 
+#[track_caller]
+fn assert_debug_metadata(debug_output: &str, type_name: &str) {
+    assert!(debug_output.starts_with(type_name));
+    assert!(debug_output.contains("layout"));
+    assert!(debug_output.contains("length"));
+    assert!(debug_output.contains("capacity"));
+    assert!(!debug_output.contains("vtable"));
+    assert!(!debug_output.contains("0x"));
+    assert!(!debug_output.contains("42"));
+}
+
+#[test]
+fn test_debug_implementations_expose_only_metadata() {
+    let mut erased = TypeErasedVec::new(vec![42_u32]);
+    assert_debug_metadata(&format!("{erased:?}"), "TypeErasedVec");
+
+    {
+        let guard = unsafe { erased.cast_type::<u32>() };
+        assert_debug_metadata(&format!("{guard:?}"), "ContentGuard");
+    }
+
+    let send_erased = SendTypeErasedVec::new(vec![42_u32]);
+    assert_debug_metadata(&format!("{send_erased:?}"), "SendTypeErasedVec");
+
+    let send_sync_erased = SendSyncTypeErasedVec::new(vec![42_u32]);
+    assert_debug_metadata(
+        &format!("{send_sync_erased:?}"),
+        "SendSyncTypeErasedVec",
+    );
+}
+
 #[test]
 fn test_sendable_is_send_sync() {
     fn assert_send<T: Send>() {}