cdh: add drop guard for close_device in tests

Similar to the drop guard for cleaning up the LUKS header file, add a
drop guard for close_device, ensuring the device will be closed even
in case of a panic.
Observed /dev/mapper across local test runs to ensure nothing is left
behind.

Signed-off-by: Manuel Huber <manuelh@nvidia.com>

Author: manuelh-dev

confidential-data-hub/hub/src/storage/drivers/luks2.rs

@@ -196,6 +196,14 @@ mod tests {
         }
     }
 
+    /// Closes the dm-crypt device on drop so tests don't leave mapper devices behind.
+    struct CloseDeviceOnDrop(String);
+    impl Drop for CloseDeviceOnDrop {
+        fn drop(&mut self) {
+            let _ = Luks2Formatter::default().close_device(&self.0);
+        }
+    }
+
     #[test]
     #[serial]
     fn encrypt_open_device_no_integrity() {
@@ -216,8 +224,7 @@ mod tests {
         luks2_formatter
             .open_device(path, None, NAME, passphrase)
             .unwrap();
-
-        luks2_formatter.close_device(NAME).unwrap();
+        let _device_guard = CloseDeviceOnDrop(NAME.to_string());
     }
 
     #[test]
@@ -240,8 +247,7 @@ mod tests {
         luks2_formatter
             .open_device(path, None, NAME, passphrase)
             .unwrap();
-
-        luks2_formatter.close_device(NAME).unwrap();
+        let _device_guard = CloseDeviceOnDrop(NAME.to_string());
     }
 
     #[test]
@@ -266,8 +272,7 @@ mod tests {
         luks2_formatter
             .open_device(path, Some(&header_path), NAME, passphrase)
             .unwrap();
-
-        luks2_formatter.close_device(NAME).unwrap();
+        let _device_guard = CloseDeviceOnDrop(NAME.to_string());
     }
 
     #[test]
@@ -292,8 +297,7 @@ mod tests {
         luks2_formatter
             .open_device(path, Some(&header_path), NAME, passphrase)
             .unwrap();
-
-        luks2_formatter.close_device(NAME).unwrap();
+        let _device_guard = CloseDeviceOnDrop(NAME.to_string());
     }
 
     #[test]