Added support to run unit tests in a multithreaded context

- This is controlled by specifying the 'mtstress' argument when running
  `unit_test`.
- The goal is to detect if the operator/transformation  fails in this
  context.
- In this mode, the test will be executed 5'000 times in 50 threads
  concurrently.
- Allocation & initialization of the operator/transformation is
  performed once in the main thread, while the evaluation is executed in
  the threads.
  - This is consistent with the library's support for multithreading,
    where initialization and loading of rules is expected to run once.
    See issue #3215.

test/unit/unit.cc

@@ -15,7 +15,9 @@
 
 #include <string.h>
 #include <cstring>
-
+#include <cassert>
+#include <thread>
+#include <array>
 #include <iostream>
 #include <ctime>
 #include <string>
@@ -38,6 +40,7 @@
 
 
 using modsecurity_test::UnitTest;
+using modsecurity_test::UnitTestResult;
 using modsecurity_test::ModSecurityTest;
 using modsecurity_test::ModSecurityTestResults;
 using modsecurity::actions::transformations::Transformation;
@@ -53,64 +56,149 @@ void print_help() {
 }
 
 
-void perform_unit_test(ModSecurityTest<UnitTest> *test, UnitTest *t,
-    ModSecurityTestResults<UnitTest>* res) {
-    std::string error;
+struct OperatorTest {
+    using ItemType = Operator;
+
+    static ItemType* init(const UnitTest &t) {
+        auto op = Operator::instantiate(t.name, t.param);
+        assert(op != nullptr);
+
+        std::string error;
+        op->init(t.filename, &error);
+
+        return op;
+    }
+
+    static UnitTestResult eval(ItemType &op, const UnitTest &t) {
+        return {op.evaluate(nullptr, nullptr, t.input, nullptr), {}};
+    }
+
+    static bool check(const UnitTestResult &result, const UnitTest &t) {
+        return result.ret != t.ret;
+    }
+};
+
+
+struct TransformationTest {
+    using ItemType = Transformation;
+
+    static ItemType* init(const UnitTest &t) {
+        auto tfn = Transformation::instantiate("t:" + t.name);
+        assert(tfn != nullptr);
+
+        return tfn;
+    }
+
+    static UnitTestResult eval(ItemType &tfn, const UnitTest &t) {
+        return {1, tfn.evaluate(t.input, nullptr)};
+    }
+
+    static bool check(const UnitTestResult &result, const UnitTest &t) {
+        return result.output != t.output;
+    }
+};
+
+
+template<typename TestType>
+UnitTestResult perform_unit_test_once(const UnitTest &t) {
+    std::unique_ptr<typename TestType::ItemType> item(TestType::init(t));
+    assert(item.get() != nullptr);
+
+    return TestType::eval(*item.get(), t);
+}
+
+
+template<typename TestType>
+UnitTestResult perform_unit_test_multithreaded(const UnitTest &t) {
+
+    constexpr auto NUM_THREADS = 50;
+    constexpr auto ITERATIONS = 5'000;
+
+    std::array<std::thread, NUM_THREADS> threads;
+    std::array<UnitTestResult, NUM_THREADS> results;
+
+    std::unique_ptr<typename TestType::ItemType> item(TestType::init(t));
+    assert(item.get() != nullptr);
+
+    for (auto i = 0; i != threads.size(); ++i)
+    {
+        auto &result = results[i];
+        threads[i] = std::thread(
+            [&item, &t, &result]()
+            {
+                for (auto j = 0; j != ITERATIONS; ++j)
+                    result = TestType::eval(*item.get(), t);
+            });
+    }
+
+    UnitTestResult ret;
+
+    for (auto i = 0; i != threads.size(); ++i)
+    {
+        threads[i].join();
+        if (TestType::check(results[i], t))
+            ret = results[i];   // error value, keep iterating to join all threads
+        else if(i == 0)
+            ret = results[i];   // initial value
+    }
+
+    return ret; // cppcheck-suppress uninitvar ; false positive, ret assigned at least once in previous loop
+}
+
+
+template<typename TestType>
+void perform_unit_test_helper(const ModSecurityTest<UnitTest> &test, UnitTest &t,
+    ModSecurityTestResults<UnitTest> &res) {
+
+    if (!test.m_test_multithreaded)
+        t.result = perform_unit_test_once<TestType>(t);
+    else
+        t.result = perform_unit_test_multithreaded<TestType>(t);
+
+    if (TestType::check(t.result, t)) {
+        res.push_back(&t);
+        if (test.m_automake_output) {
+            std::cout << "FAIL ";
+        }
+    } else if (test.m_automake_output) {
+        std::cout << "PASS ";
+    }
+}
+
+
+void perform_unit_test(const ModSecurityTest<UnitTest> &test, UnitTest &t,
+    ModSecurityTestResults<UnitTest> &res) {
     bool found = true;
 
-    if (test->m_automake_output) {
+    if (test.m_automake_output) {
         std::cout << ":test-result: ";
     }
 
-    if (t->resource.empty() == false) {
-        found = (std::find(resources.begin(), resources.end(), t->resource)
-            != resources.end());
+    if (t.resource.empty() == false) {
+        found = std::find(resources.begin(), resources.end(), t.resource)
+            != resources.end();
     }
 
     if (!found) {
-        t->skipped = true;
-        res->push_back(t);
-        if (test->m_automake_output) {
+        t.skipped = true;
+        res.push_back(&t);
+        if (test.m_automake_output) {
             std::cout << "SKIP ";
         }
     }
 
-    if (t->type == "op") {
-        Operator *op = Operator::instantiate(t->name, t->param);
-        op->init(t->filename, &error);
-        int ret = op->evaluate(NULL, NULL, t->input, NULL);
-        t->obtained = ret;
-        if (ret != t->ret) {
-            res->push_back(t);
-            if (test->m_automake_output) {
-                std::cout << "FAIL ";
-            }
-        } else if (test->m_automake_output) {
-            std::cout << "PASS ";
-        }
-        delete op;
-    } else if (t->type == "tfn") {
-        Transformation *tfn = Transformation::instantiate("t:" + t->name);
-        std::string ret = tfn->evaluate(t->input, NULL);
-        t->obtained = 1;
-        t->obtainedOutput = ret;
-        if (ret != t->output) {
-            res->push_back(t);
-            if (test->m_automake_output) {
-                std::cout << "FAIL ";
-            }
-        } else if (test->m_automake_output) {
-            std::cout << "PASS ";
-        }
-        delete tfn;
+    if (t.type == "op") {
+        perform_unit_test_helper<OperatorTest>(test, t, res);
+    } else if (t.type == "tfn") {
+        perform_unit_test_helper<TransformationTest>(test, t, res);
     } else {
-        std::cerr << "Failed. Test type is unknown: << " << t->type;
+        std::cerr << "Failed. Test type is unknown: << " << t.type;
         std::cerr << std::endl;
     }
 
-    if (test->m_automake_output) {
-        std::cout << t->name << " "
-            << modsecurity::utils::string::toHexIfNeeded(t->input)
+    if (test.m_automake_output) {
+        std::cout << t.name << " "
+            << modsecurity::utils::string::toHexIfNeeded(t.input)
             << std::endl;
     }
 }
@@ -151,17 +239,15 @@ int main(int argc, char **argv) {
         test.load_tests("test-cases/secrules-language-tests/transformations");
     }
 
-    for (std::pair<std::string, std::vector<UnitTest *> *> a : test) {
-        std::vector<UnitTest *> *tests = a.second;
-
+    for (auto& [filename, tests] : test) {
         total += tests->size();
-        for (UnitTest *t : *tests) {
+        for (auto t : *tests) {
             ModSecurityTestResults<UnitTest> r;
 
             if (!test.m_automake_output) {
-                std::cout << "  " << a.first << "...\t";
+                std::cout << "  " << filename << "...\t";
             }
-            perform_unit_test(&test, t, &r);
+            perform_unit_test(test, *t, r);
 
             if (!test.m_automake_output) {
                 int skp = 0;
@@ -191,7 +277,7 @@ int main(int argc, char **argv) {
         std::cout << "Total >> "  << total << std::endl;
     }
 
-    for (UnitTest *t : results) {
+    for (const auto t : results) {
         std::cout << t->print() << std::endl;
     }
 
@@ -216,8 +302,8 @@ int main(int argc, char **argv) {
     }
 
     for (auto a : test) {
-        auto *vec = a.second;
-        for(auto *t : *vec)
+        auto vec = a.second;
+        for(auto t : *vec)
             delete t;
         delete vec;
     }