Add test for box_pool with CamelCase types

Author: newAM

src/pool/boxed.rs

@@ -100,6 +100,7 @@ macro_rules! box_pool {
             type Data = $data_type;
 
             fn singleton() -> &'static $crate::pool::boxed::BoxPoolImpl<$data_type> {
+                #[allow(non_upper_case_globals)]
                 static $name: $crate::pool::boxed::BoxPoolImpl<$data_type> =
                     $crate::pool::boxed::BoxPoolImpl::new();
 
@@ -557,4 +558,10 @@ mod tests {
         assert!(once.is_ok());
         assert!(twice.is_ok());
     }
+
+    #[test]
+    fn box_pool_case() {
+        // https://github.com/rust-embedded/heapless/issues/411
+        box_pool!(CamelCaseType: u128);
+    }
 }