2 files changed, 40 insertions, 0 deletions
diff --git a/toolkit/components/uniffi-fixtures/refcounts/src/lib.rs b/toolkit/components/uniffi-fixtures/refcounts/src/lib.rs
new file mode 100644
index 0000000000..6554625c62
--- /dev/null
+++ b/toolkit/components/uniffi-fixtures/refcounts/src/lib.rs
@@ -0,0 +1,32 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/// This crate exists to test managing the Rust Arc strong counts as JS objects are
+/// created/destroyed.  See `test_refcounts.js` for how it's used.
+use std::sync::{Arc, Mutex};
+
+pub struct SingletonObject;
+
+impl SingletonObject {
+    pub fn method(&self) {}
+}
+
+static SINGLETON: Mutex<Option<Arc<SingletonObject>>> = Mutex::new(None);
+
+pub fn get_singleton() -> Arc<SingletonObject> {
+    Arc::clone(
+        SINGLETON
+            .lock()
+            .unwrap()
+            .get_or_insert_with(|| Arc::new(SingletonObject)),
+    )
+}
+
+pub fn get_js_refcount() -> i32 {
+    // Subtract 2: one for the reference in the Mutex and one for the temporary reference that
+    // we're calling Arc::strong_count on.
+    (Arc::strong_count(&get_singleton()) as i32) - 2
+}
+
+include!(concat!(env!("OUT_DIR"), "/refcounts.uniffi.rs"));
diff --git a/toolkit/components/uniffi-fixtures/refcounts/src/refcounts.udl b/toolkit/components/uniffi-fixtures/refcounts/src/refcounts.udl
new file mode 100644
index 0000000000..25ec83cfcc
--- /dev/null
+++ b/toolkit/components/uniffi-fixtures/refcounts/src/refcounts.udl
@@ -0,0 +1,8 @@
+namespace refcounts {
+    SingletonObject get_singleton();
+    i32 get_js_refcount();
+};
+
+interface SingletonObject {
+   void method();
+};