test: Add basic check for nChainTx type

Author: fjahr

src/test/blockchain_tests.cpp

@@ -110,4 +110,11 @@ BOOST_FIXTURE_TEST_CASE(get_prune_height, TestChain100Setup)
     CheckGetPruneHeight(blockman, chain, 100);
 }
 
+BOOST_AUTO_TEST_CASE(num_chain_tx_max)
+{
+    CBlockIndex block_index{};
+    block_index.nChainTx = std::numeric_limits<uint64_t>::max();
+    BOOST_CHECK_EQUAL(block_index.nChainTx, std::numeric_limits<uint64_t>::max());
+}
+
 BOOST_AUTO_TEST_SUITE_END()