Move AdditionOverflow to util, Add CheckedAdd with unit tests

1 files changed, 33 insertions, 0 deletions

diff --git a/src/test/util_tests.cpp b/src/test/util_tests.cpp
index 9540cead24..bc3ef9f7f1 100644
--- a/src/test/util_tests.cpp
+++ b/src/test/util_tests.cpp
@@ -15,6 +15,7 @@
 #include <util/getuniquepath.h>
 #include <util/message.h> // For MessageSign(), MessageVerify(), MESSAGE_MAGIC
 #include <util/moneystr.h>
+#include <util/overflow.h>
 #include <util/spanparsing.h>
 #include <util/strencodings.h>
 #include <util/string.h>
@@ -1463,6 +1464,38 @@ BOOST_AUTO_TEST_CASE(test_IsDigit)
     BOOST_CHECK_EQUAL(IsDigit(9), false);
 }
 
+/* Check for overflow */
+template <typename T>
+static void TestAddMatrixOverflow()
+{
+    constexpr T MAXI{std::numeric_limits<T>::max()};
+    BOOST_CHECK(!CheckedAdd(T{1}, MAXI));
+    BOOST_CHECK(!CheckedAdd(MAXI, MAXI));
+    BOOST_CHECK_EQUAL(0, CheckedAdd(T{0}, T{0}).value());
+    BOOST_CHECK_EQUAL(MAXI, CheckedAdd(T{0}, MAXI).value());
+    BOOST_CHECK_EQUAL(MAXI, CheckedAdd(T{1}, MAXI - 1).value());
+}
+
+/* Check for overflow or underflow */
+template <typename T>
+static void TestAddMatrix()
+{
+    TestAddMatrixOverflow<T>();
+    constexpr T MINI{std::numeric_limits<T>::min()};
+    constexpr T MAXI{std::numeric_limits<T>::max()};
+    BOOST_CHECK(!CheckedAdd(T{-1}, MINI));
+    BOOST_CHECK(!CheckedAdd(MINI, MINI));
+    BOOST_CHECK_EQUAL(MINI, CheckedAdd(T{0}, MINI).value());
+    BOOST_CHECK_EQUAL(MINI, CheckedAdd(T{-1}, MINI + 1).value());
+    BOOST_CHECK_EQUAL(-1, CheckedAdd(MINI, MAXI).value());
+}
+
+BOOST_AUTO_TEST_CASE(util_overflow)
+{
+    TestAddMatrixOverflow<unsigned>();
+    TestAddMatrix<signed>();
+}
+
 BOOST_AUTO_TEST_CASE(test_ParseInt32)
 {
     int32_t n;