test(miniscript): Prove avoidance of stack overflow

hodlinator · l0rinc · hodlinator · commit 7909f9f7d6d7 · 2025-12-18T16:23:41.000+01:00
Can be tested through emptying the function body of ~Node() or replacing Clone() implementation with naive version:
```C++
Node&lt;Key&gt; Clone() const
{
    std::vector&lt;Node&gt; new_subs;
    new_subs.reserve(subs.size());
    for (const Node&amp; child : subs) {
        new_subs.push_back(child.Clone());
    }
    return Node{internal::NoDupCheck{}, m_script_ctx, fragment, std::move(new_subs), keys, data, k};
}
```

Co-authored-by: Lőrinc &lt;pap.lorinc@gmail.com&gt;
diff --git a/src/test/miniscript_tests.cpp b/src/test/miniscript_tests.cpp
@@ -727,4 +727,25 @@ BOOST_AUTO_TEST_CASE(fixed_tests)
     g_testdata.reset();
 }
 
+// Confirm that ~Node(), Node::Clone() and operator=(Node&&) are stack-safe.
+BOOST_AUTO_TEST_CASE(node_deep_destruct)
+{
+    using miniscript::internal::NoDupCheck;
+    using miniscript::Fragment;
+    using NodeU32 = miniscript::Node<uint32_t>;
+
+    constexpr auto ctx{miniscript::MiniscriptContext::P2WSH};
+
+    NodeU32 root{NoDupCheck{}, ctx, Fragment::JUST_1};
+    for (uint32_t i{0}; i < 200'000; ++i) {
+        root = NodeU32{NoDupCheck{}, ctx, Fragment::WRAP_S, Vector(std::move(root))};
+    }
+    BOOST_CHECK_EQUAL(root.ScriptSize(), 200'001);
+
+    auto clone{root.Clone()};
+    BOOST_CHECK_EQUAL(clone.ScriptSize(), root.ScriptSize());
+
+    clone = std::move(root);
+}
+
 BOOST_AUTO_TEST_SUITE_END()
