Add test of GC

src/green/builder.rs

@@ -83,6 +83,13 @@ impl Builder {
         Self::default()
     }
 
+    /// The number of cached elements.
+    pub fn size(&self) -> usize {
+        self.nodes.len() + self.tokens.len()
+    }
+}
+
+impl Builder {
     /// Create a new node or clone a new Arc to an existing equivalent one.
     ///
     /// This checks children for identity equivalence, not structural,
@@ -149,7 +156,9 @@ impl Builder {
         };
         Arc::clone(token)
     }
+}
 
+impl Builder {
     fn turn_node_gc(&mut self) -> bool {
         // NB: `drain_filter` is `retain` but with an iterator of the removed elements.
         // i.e.: elements where the predicate is FALSE are removed and iterated over.

tests/gc.rs

@@ -0,0 +1,33 @@
+use sorbus::*;
+
+#[test]
+fn works_properly() {
+    let kind0 = Kind(0);
+    let kind1 = Kind(1);
+    let kind2 = Kind(2);
+    let mut builder = green::TreeBuilder::new();
+
+    #[rustfmt::skip]
+    let inner = builder
+        .start_node(kind1)
+            .token(kind0, "kind")
+        .finish_node()
+    .finish();
+
+    #[rustfmt::skip]
+    let outer = builder
+        .start_node(kind2)
+            .add(inner.clone())
+        .finish_node()
+    .finish();
+
+    assert_eq!(builder.builder().size(), 3);
+
+    drop(outer);
+    builder.builder().gc();
+    assert_eq!(builder.builder().size(), 2);
+
+    drop(inner);
+    builder.builder().gc();
+    assert_eq!(builder.builder().size(), 0);
+}