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scylladb/tests/observable_test.cc

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C++

/*
* Copyright (C) 2018 ScyllaDB
*/
/*
* This file is part of Scylla.
*
* Scylla is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Scylla is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
*/
#define BOOST_TEST_MODULE observable_test
#include <boost/test/unit_test.hpp>
#include <variant>
#include <numeric>
#include "../utils/observable.hh"
using namespace utils;
BOOST_AUTO_TEST_CASE(test_basic_functionality) {
observable<int> pub;
int v1 = 0, v2 = 0;
observer<int> sub1 = pub.observe([&] (int x) { v1 = x; });
observer<int> sub2 = pub.observe([&] (int x) { v2 = x; });
pub(7);
BOOST_REQUIRE_EQUAL(v1, 7);
BOOST_REQUIRE_EQUAL(v2, 7);
sub1.disconnect();
pub(3);
BOOST_REQUIRE_EQUAL(v1, 7);
BOOST_REQUIRE_EQUAL(v2, 3);
sub1 = std::move(sub2);
pub(4);
BOOST_REQUIRE_EQUAL(v1, 7);
BOOST_REQUIRE_EQUAL(v2, 4);
pub = observable<int>();
pub(5);
BOOST_REQUIRE_EQUAL(v1, 7);
BOOST_REQUIRE_EQUAL(v2, 4);
}
BOOST_AUTO_TEST_CASE(test_exceptions) {
observable<> pub;
bool saw1 = false;
observer<> sub1 = pub.observe([&] { saw1 = true; });
observer<> sub2 = pub.observe([&] { throw 2; });
bool saw3 = false;
observer<> sub3 = pub.observe([&] { saw3 = true; });
observer<> sub4 = pub.observe([&] { throw 4; });
bool caught = false;
try {
pub();
} catch (int v) {
BOOST_REQUIRE(saw1);
BOOST_REQUIRE(saw3);
BOOST_REQUIRE(v == 2 || v == 4);
caught = true;
}
BOOST_REQUIRE(caught);
}
BOOST_AUTO_TEST_CASE(test_disconnect_fully_disconnects) {
std::variant<observable<>, std::array<char, 100>> pub = observable<>();
observer<> sub = std::get<observable<>>(pub).observe([] {});
sub.disconnect();
auto x = std::array<char, 100>{};
std::iota(x.begin(), x.end(), 'X');
// Once upon a time, disconnect() still remembered the observable's address.
// Simulate a the observable being freed and its memory reused for something
// else by assigning garbage to the variant that holds its data
pub = x;
// Would have accessed the overwritten observable before the bug fix.
sub.disconnect();
}