[#2658] add unit tests for big ints

diff --git a/src/lib/util/tests/Makefile.am b/src/lib/util/tests/Makefile.am
index 8b6a612e75b0003694e1f8f68f937b8fd09c5b14..5f8b1e8570130e26ee7e37a8507e194269197048 100644 (file)
--- a/src/lib/util/tests/Makefile.am
+++ b/src/lib/util/tests/Makefile.am
@@ -23,6 +23,7 @@ TESTS =
 if HAVE_GTEST
 TESTS += run_unittests
 run_unittests_SOURCES  = run_unittests.cc
+run_unittests_SOURCES += bigint_unittest.cc
 run_unittests_SOURCES += base32hex_unittest.cc
 run_unittests_SOURCES += base64_unittest.cc
 run_unittests_SOURCES += boost_time_utils_unittest.cc

diff --git a/src/lib/util/tests/bigint_unittest.cc b/src/lib/util/tests/bigint_unittest.cc
new file mode 100644 (file)
index 0000000..01d3463
--- /dev/null
+++ b/src/lib/util/tests/bigint_unittest.cc
@@ -0,0 +1,94 @@
+// Copyright (C) 2023 Internet Systems Consortium, Inc. ("ISC")
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#include <config.h>
+
+#include <testutils/gtest_utils.h>
+#include <util/bigints.h>
+
+#include <gtest/gtest.h>
+
+using namespace isc::util;
+
+namespace {
+
+// C++ doesn't allow very big integer literals, so that's why some tests on big
+// numbers might appear like they're unnecessarily circumventing a more obvious
+// test choice.
+
+// Checks that int128_t behaves like a signed integer should.
+TEST(BigintTest, int128) {
+    // Check addition with small numbers.
+    EXPECT_EQ(24, int128_t(16) + int128_t(8));
+
+    // Check subtraction with small numbers.
+    EXPECT_EQ(48, int128_t(64) - int128_t(16));
+
+    // Check multiplication with small numbers.
+    EXPECT_EQ(8, int128_t(2) * int128_t(4));
+
+    // Check division with small numbers.
+    EXPECT_EQ(16, int128_t(64) / int128_t(4));
+
+    // Check rounded division with small numbers.
+    EXPECT_EQ(16, int128_t(65) / int128_t(4));
+
+    // Check that dividing by zero throws.
+    EXPECT_THROW_MSG(int128_t(1) / 0, std::overflow_error, "Division by zero.");
+
+    // Check that underflowing results in a negative number for int128_t.
+    EXPECT_EQ(-1, int128_t(0) - 1);
+
+    // Check that UINT64_MAX < INT128_MAX.
+    EXPECT_LT(uint64_t(0) - 1, int128_t(uint128_t(0) - 1));
+
+    // Check that int128_t is default-initialized to zero. Not a strict
+    // requirement, but something that the current implementation ensures.
+    int128_t i128;
+    EXPECT_EQ(0, i128);
+
+    // Check that overflowing on big numbers has the correct result.
+    i128 = int128_t(0) - 1;
+    EXPECT_EQ(i128 - 1, i128 + i128);
+}
+
+// Checks that uint128_t behaves like an unsigned integer should.
+TEST(BigintTest, uint128) {
+    // Check addition with small numbers.
+    EXPECT_EQ(24, uint128_t(16) + uint128_t(8));
+
+    // Check subtraction with small numbers.
+    EXPECT_EQ(48, uint128_t(64) - uint128_t(16));
+
+    // Check multiplication with small numbers.
+    EXPECT_EQ(8, uint128_t(2) * uint128_t(4));
+
+    // Check division with small numbers.
+    EXPECT_EQ(16, uint128_t(64) / uint128_t(4));
+
+    // Check rounded division with small numbers.
+    EXPECT_EQ(16, uint128_t(65) / uint128_t(4));
+
+    // Check that dividing by zero throws.
+    EXPECT_THROW_MSG(uint128_t(1) / 0, std::overflow_error, "Division by zero.");
+
+    // Check that underflowing results in a positive number for uint128_t.
+    EXPECT_LT(0, uint128_t(0) - 1);
+
+    // Check that UINT64_MAX < UINT128_MAX.
+    EXPECT_LT(uint64_t(0) - 1, uint128_t(0) - 1);
+
+    // Check that uint128_t is default-initialized to zero. Not a strict
+    // requirement, but something that the current implementation ensures.
+    uint128_t u128;
+    EXPECT_EQ(0, u128);
+
+    // Check that overflowing on big numbers has the correct result.
+    u128 = uint128_t(0) - 1;
+    EXPECT_EQ(u128 - 1, u128 + u128);
+}
+
+}  // namespace