Add concurrent testing for tr!

tests/multi_threading.rs

@@ -2,7 +2,7 @@ use std::ops::Add;
 use std::thread::spawn;
 use std::time::{Duration, Instant};
 
-use rust_i18n::{set_locale, t};
+use rust_i18n::{set_locale, t, tr};
 
 rust_i18n::i18n!("locales", fallback = "en");
 
@@ -32,3 +32,43 @@ fn test_load_and_store() {
     store.join().unwrap();
     load.join().unwrap();
 }
+
+#[test]
+fn test_tr_concurrent() {
+    let end = Instant::now().add(Duration::from_secs(3));
+    let store = spawn(move || {
+        let mut i = 0u32;
+        while Instant::now() < end {
+            for _ in 0..100 {
+                i = i.wrapping_add(1);
+                if i % 2 == 0 {
+                    set_locale(&format!("en-{i}"));
+                } else {
+                    set_locale(&format!("fr-{i}"));
+                }
+            }
+        }
+    });
+    let tasks: Vec<_> = (0..4)
+        .map(|_| {
+            spawn(move || {
+                let locales = rust_i18n::available_locales!();
+                let num_locales = locales.len();
+                while Instant::now() < end {
+                    for i in 0..100 {
+                        let m = i % num_locales;
+                        if m == 0 {
+                            tr!("hello");
+                        } else {
+                            tr!("hello", locale = locales[m]);
+                        }
+                    }
+                }
+            })
+        })
+        .collect();
+    store.join().unwrap();
+    for task in tasks {
+        task.join().unwrap();
+    }
+}