Example tests in crate (#585)

bdwgc-alloc/Cargo.toml

@@ -18,3 +18,7 @@ cmake = ["bdwgc-alloc-sys/cmake"]
 
 [lints]
 workspace = true
+
+[[test]]
+name = "allocator"
+harness = false

bdwgc-alloc/tests/allocator.rs

@@ -0,0 +1,53 @@
+//! A smoke test of the allocator.
+
+use bdwgc_alloc::Allocator;
+use core::hint::black_box;
+use std::thread::spawn;
+
+const OBJECT_SIZE: usize = 1 << 8;
+const TOTAL_COUNT: usize = 1 << 16;
+const THREAD_COUNT: usize = 1 << 6;
+
+#[global_allocator]
+static GLOBAL_ALLOCATOR: Allocator = Allocator;
+
+fn main() {
+    unsafe { Allocator::initialize() }
+
+    free_by_gc();
+    free_by_drop();
+    static_thread();
+    dynamic_threads();
+}
+
+fn free_by_gc() {
+    for _ in 0..TOTAL_COUNT {
+        black_box(Box::leak(Box::new([0u8; OBJECT_SIZE])));
+    }
+}
+
+fn free_by_drop() {
+    for _ in 0..TOTAL_COUNT {
+        drop(black_box(Box::new([0u8; OBJECT_SIZE])));
+    }
+}
+
+fn static_thread() {
+    spawn_thread(free_by_gc);
+}
+
+fn dynamic_threads() {
+    for _ in 0..THREAD_COUNT {
+        spawn_thread(free_by_gc);
+    }
+}
+
+fn spawn_thread(allocate: fn()) {
+    spawn(move || {
+        unsafe { Allocator::register_current_thread() }.unwrap();
+        allocate();
+        unsafe { Allocator::unregister_current_thread() }
+    })
+    .join()
+    .unwrap();
+}