test: fix invalid value for max_background_threads

0 is invalid and will be banned in the latest version.

Signed-off-by: Jay Lee <busyjaylee@gmail.com>

Author: BusyJay

jemalloc-ctl/src/macros.rs

@@ -91,7 +91,7 @@ macro_rules! r {
 
 /// Write
 macro_rules! w {
-    ($id:ident => $ret_ty:ty) => {
+    ($id:ident => ($ret_ty:ty | $test_val:expr)) => {
         paste::paste! {
             impl $id {
                 /// Writes `value` using string API.
@@ -112,29 +112,37 @@ macro_rules! w {
             #[cfg(test)]
             #[test]
             fn [<$id _write_test>]() {
-                match stringify!($id) {
-                    "background_thread" |
-                    "max_background_threads"
-                        if cfg!(target_os = "macos") => return,
-                    _ => (),
+                if (cfg!(target_os = "macos") && (stringify!($id) == "background_thread"
+                    || stringify!($id) == "max_background_threads")) {
+                    return;
                 }
 
-                let _ = $id::write($ret_ty::default()).unwrap();
+                let test_val = $test_val;
+
+                let _ = $id::write(test_val).unwrap();
 
                 let mib = $id::mib().unwrap();
-                let _ = mib.write($ret_ty::default()).unwrap();
+                let _ = mib.write(test_val).unwrap();
 
                 #[cfg(feature = "use_std")]
                 println!(
                     concat!(
                         stringify!($id),
                         " (write): \"{}\""),
-                    $ret_ty::default()
+                    test_val
                 );
 
             }
         }
     };
+    (max_background_threads => $ret_ty:ty) => {
+        // non-zero
+        w!(max_background_threads => ($ret_ty | 1));
+    };
+    ($id:ident => $ret_ty:ty) => {
+        // general case
+        w!($id => ($ret_ty | Default::default()));
+    };
 }
 
 /// Update