From 8333abdd916c506f778ef9a095e684e12b7fed9e Mon Sep 17 00:00:00 2001
From: optout <13562139+optout21@users.noreply.github.com>
Date: Tue, 20 Jan 2026 16:58:53 +0100
Subject: [PATCH] test: Add CChain basic tests

Add basic unit tests to the `CChain` class, filling a gap.

Co-authored-by: l0rinc <pap.lorinc@gmail.com>
---
 src/test/chain_tests.cpp | 44 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/src/test/chain_tests.cpp b/src/test/chain_tests.cpp
index a782e880f9f..d2d68289e73 100644
--- a/src/test/chain_tests.cpp
+++ b/src/test/chain_tests.cpp
@@ -41,6 +41,50 @@ const CBlockIndex* NaiveLastCommonAncestor(const CBlockIndex* a, const CBlockInd
 
 } // namespace
 
+BOOST_AUTO_TEST_CASE(basic_tests)
+{
+    // An empty chain
+    const CChain chain_0;
+    // A chain with 2 blocks
+    CChain chain_2;
+
+    CBlockIndex genesis;
+    genesis.nHeight = 0;
+    chain_2.SetTip(genesis);
+
+    CBlockIndex bi1;
+    bi1.pprev = &genesis;
+    bi1.nHeight = 1;
+    chain_2.SetTip(bi1);
+
+    BOOST_CHECK_EQUAL(chain_0.Height(), -1);
+    BOOST_CHECK_EQUAL(chain_2.Height(), 1);
+
+    BOOST_CHECK_EQUAL(chain_0.Tip(), nullptr);
+    BOOST_CHECK_EQUAL(chain_2.Tip(), &bi1);
+
+    // Indexer accessor: call with valid and invalid (low & high) values
+    BOOST_CHECK_EQUAL(chain_2[-1], nullptr);
+    BOOST_CHECK_EQUAL(chain_2[0], &genesis);
+    BOOST_CHECK_EQUAL(chain_2[1], &bi1);
+    BOOST_CHECK_EQUAL(chain_2[2], nullptr);
+
+    // Contains: call with contained & non-contained blocks
+    BOOST_CHECK(chain_2.Contains(&genesis));
+    BOOST_CHECK(chain_2.Contains(&bi1));
+    BOOST_CHECK(!chain_0.Contains(&genesis));
+    // BOOST_CHECK(!chain_0.Contains(nullptr)); // fail with memory access violation
+
+    // Call with non-tip & tip blocks
+    BOOST_CHECK_EQUAL(chain_2.Next(&genesis), &bi1);
+    BOOST_CHECK_EQUAL(chain_2.Next(&bi1), nullptr);
+    BOOST_CHECK_EQUAL(chain_0.Next(&genesis), nullptr);
+    // BOOST_CHECK_EQUAL(chain_0.Next(nullptr), nullptr); // fail with memory access violation
+
+    BOOST_CHECK_EQUAL(chain_2.Genesis(), &genesis);
+    BOOST_CHECK_EQUAL(chain_0.Genesis(), nullptr);
+}
+
 BOOST_AUTO_TEST_CASE(chain_test)
 {
     FastRandomContext ctx;