From f9641b9efd2478929e4811209111c3ca76836d68 Mon Sep 17 00:00:00 2001 From: Jade Lovelace Date: Fri, 5 Jul 2024 15:52:55 +0200 Subject: libutil: add checked arithmetic tools This is in preparation for adding checked arithmetic to the evaluator. Change-Id: I6e115ce8f5411feda1706624977a4dcd5efd4d13 --- .../libutil-support/tests/gtest-with-params.hh | 54 +++++++ tests/unit/libutil/checked-arithmetic.cc | 158 +++++++++++++++++++++ tests/unit/meson.build | 1 + 3 files changed, 213 insertions(+) create mode 100644 tests/unit/libutil-support/tests/gtest-with-params.hh create mode 100644 tests/unit/libutil/checked-arithmetic.cc (limited to 'tests/unit') diff --git a/tests/unit/libutil-support/tests/gtest-with-params.hh b/tests/unit/libutil-support/tests/gtest-with-params.hh new file mode 100644 index 000000000..323a083fe --- /dev/null +++ b/tests/unit/libutil-support/tests/gtest-with-params.hh @@ -0,0 +1,54 @@ +#pragma once +// SPDX-FileCopyrightText: 2014 Emil Eriksson +// +// SPDX-License-Identifier: BSD-2-Clause +// +// The lion's share of this code is copy pasted directly out of RapidCheck +// headers, so the copyright is set accordingly. +/** + * @file Implements the ability to run a RapidCheck test under gtest with changed + * test parameters such as the number of tests to run. This is useful for + * running very large numbers of the extremely cheap property tests. + */ + +#include +#include +#include + +namespace rc::detail { + +using MakeTestParams = TestParams (*)(); + +template +void checkGTestWith(Testable && testable, MakeTestParams makeTestParams) +{ + const auto testInfo = ::testing::UnitTest::GetInstance()->current_test_info(); + detail::TestMetadata metadata; + metadata.id = std::string(testInfo->test_case_name()) + "/" + std::string(testInfo->name()); + metadata.description = std::string(testInfo->name()); + + const auto result = checkTestable(std::forward(testable), metadata, makeTestParams()); + + if (result.template is()) { + const auto success = result.template get(); + if (!success.distribution.empty()) { + printResultMessage(result, std::cout); + std::cout << std::endl; + } + } else { + std::ostringstream ss; + printResultMessage(result, ss); + FAIL() << ss.str() << std::endl; + } +} +} + +#define RC_GTEST_PROP_WITH_PARAMS(TestCase, Name, MakeParams, ArgList) \ + void rapidCheck_propImpl_##TestCase##_##Name ArgList; \ + \ + TEST(TestCase, Name) \ + { \ + ::rc::detail::checkGTestWith(&rapidCheck_propImpl_##TestCase##_##Name, MakeParams); \ + } \ + \ + void rapidCheck_propImpl_##TestCase##_##Name ArgList diff --git a/tests/unit/libutil/checked-arithmetic.cc b/tests/unit/libutil/checked-arithmetic.cc new file mode 100644 index 000000000..2a9ba6906 --- /dev/null +++ b/tests/unit/libutil/checked-arithmetic.cc @@ -0,0 +1,158 @@ +#include +#include +#include +#include +#include +#include + +#include + +#include "tests/gtest-with-params.hh" + +namespace rc { +using namespace nix; + +template +struct Arbitrary> +{ + static Gen> arbitrary() + { + return gen::arbitrary(); + } +}; + +} + +namespace nix::checked { + +// Pointer to member function! Mildly gross. +template +using Oper = Checked::Result (Checked::*)(T const other) const; + +template +using ReferenceOper = T (*)(T a, T b); + +/** + * Checks that performing an operation that overflows into an inaccurate result + * has the desired behaviour. + * + * TBig is a type large enough to represent all results of TSmall operations. + */ +template +void checkType(TSmall a_, TSmall b, Oper oper, ReferenceOper reference) +{ + // Sufficient to fit all values + TBig referenceResult = reference(a_, b); + constexpr const TSmall minV = std::numeric_limits::min(); + constexpr const TSmall maxV = std::numeric_limits::max(); + + Checked a{a_}; + auto result = (a.*(oper))(b); + + // Just truncate it to get the in-range result + RC_ASSERT(result.valueWrapping() == static_cast(referenceResult)); + + if (referenceResult > maxV || referenceResult < minV) { + RC_ASSERT(result.overflowed()); + RC_ASSERT(!result.valueChecked().has_value()); + } else { + RC_ASSERT(!result.overflowed()); + RC_ASSERT(result.valueChecked().has_value()); + RC_ASSERT(*result.valueChecked() == referenceResult); + } +} + +/** + * Checks that performing an operation that overflows into an inaccurate result + * has the desired behaviour. + * + * TBig is a type large enough to represent all results of TSmall operations. + */ +template +void checkDivision(TSmall a_, TSmall b) +{ + // Sufficient to fit all values + constexpr const TSmall minV = std::numeric_limits::min(); + + Checked a{a_}; + auto result = a / b; + + if (std::is_signed() && a_ == minV && b == -1) { + // This is the only possible overflow condition + RC_ASSERT(result.valueWrapping() == minV); + RC_ASSERT(result.overflowed()); + } else if (b == 0) { + RC_ASSERT(result.divideByZero()); + RC_ASSERT_THROWS_AS(result.valueWrapping(), nix::checked::DivideByZero); + RC_ASSERT(result.valueChecked() == std::nullopt); + } else { + TBig referenceResult = a_ / b; + auto result_ = result.valueChecked(); + RC_ASSERT(result_.has_value()); + RC_ASSERT(*result_ == referenceResult); + RC_ASSERT(result.valueWrapping() == referenceResult); + } +} + +/** Creates parameters that perform a more adequate number of checks to validate + * extremely cheap tests such as arithmetic tests */ +static rc::detail::TestParams makeParams() { + auto const & conf = rc::detail::configuration(); + auto newParams = conf.testParams; + newParams.maxSuccess = 10000; + return newParams; +} + +RC_GTEST_PROP_WITH_PARAMS(Checked, add_unsigned, makeParams, (uint16_t a, uint16_t b)) +{ + checkType(a, b, &Checked::operator+, [](int32_t a, int32_t b) { return a + b; }); +} + +RC_GTEST_PROP_WITH_PARAMS(Checked, add_signed, makeParams, (int16_t a, int16_t b)) +{ + checkType(a, b, &Checked::operator+, [](int32_t a, int32_t b) { return a + b; }); +} + +RC_GTEST_PROP_WITH_PARAMS(Checked, sub_unsigned, makeParams, (uint16_t a, uint16_t b)) +{ + checkType(a, b, &Checked::operator-, [](int32_t a, int32_t b) { return a - b; }); +} + +RC_GTEST_PROP_WITH_PARAMS(Checked, sub_signed, makeParams, (int16_t a, int16_t b)) +{ + checkType(a, b, &Checked::operator-, [](int32_t a, int32_t b) { return a - b; }); +} + +RC_GTEST_PROP_WITH_PARAMS(Checked, mul_unsigned, makeParams, (uint16_t a, uint16_t b)) +{ + checkType(a, b, &Checked::operator*, [](int64_t a, int64_t b) { return a * b; }); +} + + +RC_GTEST_PROP_WITH_PARAMS(Checked, mul_signed, makeParams, (int16_t a, int16_t b)) +{ + checkType(a, b, &Checked::operator*, [](int64_t a, int64_t b) { return a * b; }); +} + +RC_GTEST_PROP_WITH_PARAMS(Checked, div_unsigned, makeParams, (uint16_t a, uint16_t b)) +{ + checkDivision(a, b); +} + +RC_GTEST_PROP_WITH_PARAMS(Checked, div_signed, makeParams, (int16_t a, int16_t b)) +{ + checkDivision(a, b); +} + +// Make absolutely sure that we check the special cases if the proptest +// generator does not come up with them. This one is especially important +// because it has very specific pairs required for the edge cases unlike the +// others. +TEST(Checked, div_signed_special_cases) +{ + checkDivision(std::numeric_limits::min(), -1); + checkDivision(std::numeric_limits::min(), 0); + checkDivision(0, 0); +} + +} diff --git a/tests/unit/meson.build b/tests/unit/meson.build index a6719a060..c449b2276 100644 --- a/tests/unit/meson.build +++ b/tests/unit/meson.build @@ -35,6 +35,7 @@ liblixutil_test_support = declare_dependency( libutil_tests_sources = files( 'libutil/canon-path.cc', + 'libutil/checked-arithmetic.cc', 'libutil/chunked-vector.cc', 'libutil/closure.cc', 'libutil/compression.cc', -- cgit v1.2.3