Test free_token_node in Rust

spec/test_tree_delete_token_node_memory.rs

@@ -0,0 +1,17 @@
+use testparser::*;
+use std::sync::atomic::Ordering;
+
+fn main() {
+    let mut context = p_context_new(b"ab");
+    assert_eq!(P_SUCCESS, p_parse(&mut context));
+    let start = p_result(&context);
+    assert!(start.a().valid());
+    assert_eq!(1, unsafe { *start.a().pvalue() });
+    assert!(start.b().valid());
+    assert_eq!(2, unsafe { *start.b().pvalue() });
+
+    /* The free_token_node code block runs from p_context_delete(), not before. */
+    assert_eq!(0, FREED.load(Ordering::SeqCst));
+    p_context_delete(context);
+    assert_eq!(2, FREED.load(Ordering::SeqCst));
+}