add CMutableTransaction size test

src/Makefile.test.include

@@ -95,6 +95,7 @@ BITCOIN_TESTS =\
   test/blsct/building_block/lazy_points_tests.cpp \
   test/blsct/common_tests.cpp \
   test/blsct/eip_2333/bls12_381_keygen_tests.cpp \
+	test/blsct/external_api/blsct_tests.cpp \
   test/blsct/keys_tests.cpp \
   test/blsct/range_proof/range_proof_common_tests.cpp \
   test/blsct/range_proof/generators_tests.cpp \

src/test/blsct/external_api/blsct_tests.cpp

@@ -0,0 +1,38 @@
+// Copyright (c) 2024 The Navio developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <boost/test/unit_test.hpp>
+#include <test/util/setup_common.h>
+#include <primitives/transaction.h>
+
+#define ASSERT_SIZE_EQ(type, size) BOOST_CHECK_EQUAL(sizeof(type), size)
+
+BOOST_FIXTURE_TEST_SUITE(external_api_tests, BasicTestingSetup)
+
+// This test verifies the sizes of CMutableTransaction and
+// all user-defined types within it to detect any structural
+// changes in the CMutableTransaction class
+BOOST_AUTO_TEST_CASE(test_cmutable_transaction_sizes)
+{
+    ASSERT_SIZE_EQ(Txid, 32);
+
+    ASSERT_SIZE_EQ(CTxIn, 104);
+    ASSERT_SIZE_EQ(COutPoint, 36);
+    ASSERT_SIZE_EQ(CScript, 32);
+    ASSERT_SIZE_EQ(CScriptWitness, 24);
+
+    ASSERT_SIZE_EQ(CTxOutBLSCTData, 1248);
+    ASSERT_SIZE_EQ(MclG1Point, 144);
+    ASSERT_SIZE_EQ(bulletproofs::RangeProof<Mcl>, 808);
+
+    ASSERT_SIZE_EQ(CTxOut, 1328);
+    ASSERT_SIZE_EQ(CAmount, 8);
+    ASSERT_SIZE_EQ(TokenId, 40);
+
+    ASSERT_SIZE_EQ(CMutableTransaction, 344);
+    ASSERT_SIZE_EQ(blsct::Signature, 288);
+}
+
+BOOST_AUTO_TEST_SUITE_END()
+