Cppcheck report - cppcheck report: src/hooks/dhcp/lease_cmds/tests/binding_variables_unittest.cc

// Copyright (C) 2025 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 <lease_cmds.h><--- Include file:  not found. Please note: Cppcheck does not need standard library headers to get proper results.
#include <hooks/hooks_manager.h>
#include <dhcpsrv/cfgmgr.h>
#include <dhcpsrv/lease_mgr_factory.h>
#include <exceptions/exceptions.h>
#include <cc/data.h>
#include <dhcp/dhcp6.h>
#include <dhcp/pkt4.h>
#include <dhcp/pkt6.h>
#include <dhcpsrv/lease.h>

#include <testutils/gtest_utils.h>
#include <testutils/user_context_utils.h>
#include <testutils/multi_threading_utils.h>

#include <gtest/gtest.h>

using namespace std;
using namespace isc;
using namespace isc::dhcp;
using namespace isc::data;
using namespace isc::test;
using namespace isc::asiolink;
using namespace isc::hooks;

using namespace isc::lease_cmds;

namespace {

#define SCOPED_LINE(line) \
    std::stringstream ss; \
    ss << "Scenario at line: " << line; \
    SCOPED_TRACE(ss.str());

/// @brief Test BindingVariable valid construction scenarios.
TEST(BindingVariableTest, validConstructor) {
    BindingVariablePtr bv;

    struct Scenario {
        uint32_t line_;
        std::string name_;
        std::string expression_str_;
        BindingVariable::Source source_;
        uint32_t family_;
    };

    std::string valid_v4_exp = "pkt4.mac";
    std::string valid_v6_exp = "pkt6.transid";

    std::list<Scenario> scenarios = {
        {
           __LINE__,  "my-var", valid_v4_exp, BindingVariable::QUERY, AF_INET
        },
        {
           __LINE__,  "my-var", valid_v4_exp, BindingVariable::RESPONSE, AF_INET
        },
        {
           __LINE__,  "my-var", valid_v6_exp, BindingVariable::QUERY, AF_INET6
        },
        {
           __LINE__,  "my-var", valid_v6_exp, BindingVariable::RESPONSE, AF_INET6
        },
        {
           __LINE__,  "my-var", "'woo hoo'", BindingVariable::RESPONSE, AF_INET6
        }
    };

    for (auto const& scenario : scenarios) {
        SCOPED_LINE(scenario.line_);
        ASSERT_NO_THROW_LOG(bv.reset(new BindingVariable(scenario.name_,
                                                         scenario.expression_str_,
                                                         scenario.source_,
                                                         scenario.family_)));
        ASSERT_TRUE(bv);
        EXPECT_EQ(bv->getName(), scenario.name_);
        EXPECT_EQ(bv->getExpressionStr(), scenario.expression_str_);
        ASSERT_TRUE(bv->getExpression());
        EXPECT_EQ(bv->getSource(), scenario.source_);
        EXPECT_EQ(bv->getFamily(), scenario.family_);
    }
}

/// @brief Test BindingVariable invalid construction scenarios.
TEST(BindingVariableTest, invalidConstructor) {
    BindingVariablePtr bv;

    struct Scenario {
        uint32_t line_;
        std::string name_;
        std::string expression_str_;
        uint32_t family_;
        std::string expected_error_;
    };

    std::string valid_v4_exp = "pkt4.mac";
    std::string valid_v6_exp = "pkt6.transid";

    std::list<Scenario> scenarios = {
        {
           __LINE__,  "", valid_v4_exp, AF_INET,
           "BindingVariable - name cannot be empty"
        },
        {
           __LINE__,  "my-var", "", AF_INET,
           "BindingVariable - 'my-var' expression_str cannot be empty"
        },
        {
           __LINE__,  "my-var", "bogus + stuff", AF_INET,
           "BindingVariable - 'my-var', error parsing expression: "
           "'bogus + stuff' : <string>:1.1: Invalid character: b"
        },
        {
           __LINE__,  "my-var", valid_v4_exp, 99,
           "BindingVariable - 'my-var', invalid family: 99"
        },
        {
           __LINE__,  "my-var", valid_v4_exp, AF_INET6,
           "BindingVariable - 'my-var', error parsing expression: "
           "'pkt4.mac' : <string>:1.1-4: pkt4 can only be used in DHCPv4."
        },
        {
           __LINE__,  "my-var", valid_v6_exp, AF_INET,
           "BindingVariable - 'my-var', error parsing expression: "
           "'pkt6.transid' : <string>:1.1-4: pkt6 can only be used in DHCPv6."
        }
    };

    for (auto const& scenario : scenarios) {
        SCOPED_LINE(scenario.line_);
        ASSERT_THROW_MSG(bv.reset(new BindingVariable(scenario.name_,
                                                      scenario.expression_str_,
                                                      BindingVariable::QUERY,
                                                      scenario.family_)),
                        BadValue, scenario.expected_error_);
    }
}

/// @brief Tests BindingVariable::toElement().
TEST(BindingVariableTest, toElement) {
    BindingVariablePtr bv;

    ASSERT_NO_THROW_LOG(bv.reset(new BindingVariable("myvar",
                                                     "pkt4.mac",
                                                     BindingVariable::QUERY,
                                                     AF_INET)));
    ASSERT_TRUE(bv);
    ElementPtr elem;

    ASSERT_NO_THROW_LOG(elem = bv->toElement());
    std::stringstream ss;
    elem->toJSON(ss);
    std::string expected_json = "{ \"expression\": \"pkt4.mac\","
                                " \"name\": \"myvar\", \"source\": \"query\" }";
    EXPECT_EQ(ss.str(), expected_json);
}

/// @brief Checks BindingVariable::parse with valid scenarios.
TEST(BindingVariableTest, validParsing) {
    struct Scenario {
        uint32_t line_;
        std::string config_;
        uint32_t family_;
        std::string expected_json_;
    };

    std::list<Scenario> scenarios = {
        {
           __LINE__,
           R"({ "name": "one", "expression" : "pkt4.mac", "source": "query"})",
            AF_INET,
           "{ \"expression\": \"pkt4.mac\", \"name\": \"one\", \"source\": \"query\" }"
        },
        {
           __LINE__,
           R"({ "name": "two", "expression" : "pkt4.mac", "source": "response"})",
            AF_INET,
           "{ \"expression\": \"pkt4.mac\", \"name\": \"two\", \"source\": \"response\" }"
        },
        {
           __LINE__,
           R"({ "name": "three", "expression" : "pkt6.transid", "source": "query"})",
            AF_INET6,
           "{ \"expression\": \"pkt6.transid\", \"name\": \"three\", \"source\": \"query\" }"
        },
        {
           __LINE__,
           R"({ "name": "four", "expression" : "pkt6.transid", "source": "response"})",
            AF_INET6,
           "{ \"expression\": \"pkt6.transid\", \"name\": \"four\", \"source\": \"response\" }"
        }
    };

    for (auto const& scenario : scenarios) {
        SCOPED_LINE(scenario.line_);
        BindingVariablePtr var;
        ElementPtr config;
        ASSERT_NO_THROW_LOG(config = Element::fromJSON(scenario.config_));
        ASSERT_NO_THROW_LOG(var = BindingVariable::parse(config, scenario.family_));
        ASSERT_TRUE(var);
        std::stringstream js;
        var->toElement()->toJSON(js);
        EXPECT_EQ(js.str(), scenario.expected_json_);
    }
}

/// @brief Checks BindingVariable::parse with invalid scenarios.
TEST(BindingVariableTest, invalidParsing) {
    struct Scenario {
        uint32_t line_;
        std::string config_;
        uint32_t family_;
        std::string expected_error_;
    };

    std::list<Scenario> scenarios = {
        {
            __LINE__,
            R"({ "name": "", "expression" : "pkt4.mac", "source": "query"})",
            AF_INET,
            "invalid config: BindingVariable - name cannot be empty"
        },
        {
            __LINE__,
            R"({ "name": "myvar", "expression" : "", "source": "response"})",
            AF_INET,
            "invalid config: BindingVariable - 'myvar' expression_str cannot be empty"
        },
        {
            __LINE__,
            R"({ "name": "myvar", "expression" : "pkt5.bogus", "source": "query"})",
            AF_INET,
            "invalid config: BindingVariable - 'myvar', error parsing expression:"
            " 'pkt5.bogus' : <string>:1.4: syntax error, unexpected integer, expecting ."
        },
        {
            __LINE__,
            R"({ "name": "myvar", "expression" : "pkt4.mac", "source": "BOGUS"})",
            AF_INET,
            "invalid config: invalid source 'BOGUS', must be either 'query' or 'response'"
        },
        {
            __LINE__,
            R"({ "name": "myvar", "expression" : "pkt4.mac", "source": "query", "bogus" : "foo" })",
            AF_INET,
            "spurious 'bogus' parameter"
        }
    };

    for (auto const& scenario : scenarios) {
        SCOPED_LINE(scenario.line_);
        ElementPtr config;
        ASSERT_NO_THROW_LOG(config = Element::fromJSON(scenario.config_));
        ASSERT_THROW_MSG(BindingVariable::parse(config, scenario.family_),
                         DhcpConfigError, scenario.expected_error_);
    }
}

/// @brief Verifies basic operation of the cache including
/// construction, all getters and cache clearing.
TEST(BindingVariableCacheTest, basics) {
    // Save start time of test.  We use seconds because that's that
    // BaseStampedElement uses.
    auto ref_time = boost::posix_time::second_clock::local_time();

    // Create a new cache.
    BindingVariableCachePtr cache(new BindingVariableCache());

    // Verify last flush time has been set to approximately now.
    EXPECT_GE(cache->getLastFlushTime(), ref_time);
    ref_time = cache->getLastFlushTime();

    // Ensure getters return empty lists or pointers without harm.
    BindingVariableListPtr var_list;
    ASSERT_NO_THROW_LOG(var_list = cache->getAll());
    ASSERT_TRUE(var_list);
    EXPECT_EQ(var_list->size(), 0);

    BindingVariablePtr var;
    ASSERT_NO_THROW_LOG(var = cache->getByName("foo"));
    ASSERT_FALSE(var);

    ASSERT_NO_THROW_LOG(var_list = cache->getBySource(BindingVariable::QUERY));
    ASSERT_TRUE(var_list);
    EXPECT_EQ(var_list->size(), 0);

    ASSERT_NO_THROW_LOG(var_list = cache->getBySource(BindingVariable::RESPONSE));
    ASSERT_TRUE(var_list);
    EXPECT_EQ(var_list->size(), 0);

    // Add four variables.
    std::string valid_v6_exp = "pkt6.transid";
    BindingVariableList ref_list;
    ref_list.push_back(BindingVariablePtr(new BindingVariable("one", valid_v6_exp,
                                                              BindingVariable::QUERY,
                                                              AF_INET6)));

    ref_list.push_back(BindingVariablePtr(new BindingVariable("two", valid_v6_exp,
                                                              BindingVariable::RESPONSE,
                                                              AF_INET6)));

    ref_list.push_back(BindingVariablePtr(new BindingVariable("three", valid_v6_exp,
                                                              BindingVariable::RESPONSE,
                                                              AF_INET6)));

    ref_list.push_back(BindingVariablePtr(new BindingVariable("four", valid_v6_exp,
                                                              BindingVariable::QUERY,
                                                              AF_INET6)));

    for (auto const& ref_iter : ref_list) {
        ASSERT_NO_THROW_LOG(cache->add(ref_iter));
    }

    // Make sure getAll() returns all four in order added.
    ASSERT_NO_THROW_LOG(var_list = cache->getAll());
    ASSERT_TRUE(var_list);
    EXPECT_EQ(var_list->size(), 4);

    auto var_iter = var_list->begin();
    for (auto const& ref_iter : ref_list) {
        EXPECT_EQ((*var_iter)->getName(), ref_iter->getName());
        EXPECT_EQ((*var_iter)->getSource(), ref_iter->getSource());
        ++var_iter;
    }

    // Make sure getByName() can return each one.
    for (auto const& ref_iter : ref_list) {
        ASSERT_NO_THROW_LOG(var = cache->getByName(ref_iter->getName()));
        ASSERT_TRUE(var);
        EXPECT_EQ(var->getName(), ref_iter->getName());
    }

    // Make sure getBySource() works for QUERY.
    ASSERT_NO_THROW_LOG(var_list = cache->getBySource(BindingVariable::QUERY));
    ASSERT_TRUE(var_list);
    ASSERT_EQ(var_list->size(), 2);

    var_iter = var_list->begin();
    for (auto const& ref_iter : ref_list) {
        if (ref_iter->getSource() == BindingVariable::QUERY) {
            EXPECT_EQ((*var_iter)->getName(), ref_iter->getName());
            ++var_iter;
        }
    }

    // Make sure getBySource() works for RESPONSE.
    ASSERT_NO_THROW_LOG(var_list = cache->getBySource(BindingVariable::RESPONSE));
    ASSERT_TRUE(var_list);
    ASSERT_EQ(var_list->size(), 2);

    var_iter = var_list->begin();
    for (auto const& ref_iter : ref_list) {
        if (ref_iter->getSource() == BindingVariable::RESPONSE) {
            EXPECT_EQ((*var_iter)->getName(), ref_iter->getName());
            ++var_iter;
        }
    }

    // Make sure last flush time hasn't been touched.
    EXPECT_EQ(cache->getLastFlushTime(), ref_time);

    // Sleep 1s so we can check flush time gets updated.
    usleep(1000000);
    ASSERT_NO_THROW_LOG(cache->clear());
    EXPECT_EQ(cache->size(), 0);

    EXPECT_GT(cache->getLastFlushTime(), ref_time);
}

/// @brief Verifies cache behavior for handling duplicate entries.
TEST(BindingVariableCacheTest, duplicateEntries) {
    // Create a new cache.
    BindingVariableCachePtr cache(new BindingVariableCache());


    std::string valid_v4_exp = "pkt4.mac";
    BindingVariablePtr var1(new BindingVariable("one", valid_v4_exp,
                                                BindingVariable::QUERY,
                                                AF_INET));

    BindingVariablePtr var2(new BindingVariable("one", valid_v4_exp,
                                                BindingVariable::RESPONSE,
                                                AF_INET));

    bool add_flag;
    ASSERT_NO_THROW_LOG(add_flag = cache->add(var1));
    EXPECT_TRUE(add_flag);
    EXPECT_EQ(cache->size(), 1);

    // Make sure getByName returns the added variable.
    BindingVariablePtr found_var;
    ASSERT_NO_THROW_LOG(found_var = cache->getByName("one"));
    ASSERT_EQ(found_var->getSource(), BindingVariable::QUERY);

    // Adding a duplicate should fail.
    ASSERT_NO_THROW_LOG(add_flag = cache->add(var2));
    EXPECT_FALSE(add_flag);
    EXPECT_EQ(cache->size(), 1);

    // Make sure getByName returns the original variable.
    ASSERT_NO_THROW_LOG(found_var = cache->getByName("one"));
    ASSERT_EQ(found_var->getSource(), BindingVariable::QUERY);
}

/// @brief Tests BindingVariableMgr::configure() with valid
/// configuration scenarios.
TEST(BindingVariableMgrTest, validConfigure) {
    struct Scenario {
        uint32_t line_;
        uint32_t family_;
        std::string config_;
        std::list<std::string> expected_vars_;
    };

    std::list<Scenario> scenarios = {
    {
        __LINE__,
        AF_INET,
        R"({})",
        {}
    },{
        __LINE__,
        AF_INET,
        R"({"binding-variables":[]})",
        {}
    },{
        __LINE__,
        AF_INET,
        R"({"binding-variables":[
            {
                "name": "one",
                "expression": "pkt4.mac",
                "source": "query"
            },
            {
                "name": "two",
                "expression": "pkt4.mac",
                "source": "response"
            } ]})",
        { "one", "two" }
    },{
        __LINE__,
        AF_INET6,
        R"({"binding-variables":[
            {
                "name": "three",
                "expression": "pkt6.transid",
                "source": "query"
            },
            {
                "name": "four",
                "expression": "pkt6.transid",
                "source": "response"
            } ]})",
        { "three", "four" }
    }};

    for (auto const& scenario : scenarios) {
        SCOPED_LINE(scenario.line_);
        BindingVariableMgrPtr mgr;
        ASSERT_NO_THROW_LOG(mgr.reset(new BindingVariableMgr(scenario.family_)));
        ConstElementPtr config;
        ASSERT_NO_THROW_LOG(config = Element::fromJSON(scenario.config_));
        ASSERT_NO_THROW_LOG(mgr->configure(config));
        auto cache = mgr->getCache();
        ASSERT_TRUE(cache);
        ASSERT_EQ(cache->size(), scenario.expected_vars_.size());
        for (auto const& exp_name : scenario.expected_vars_) {
            auto const& found_var = cache->getByName(exp_name);
            ASSERT_TRUE(found_var);
            EXPECT_EQ(found_var->getName(), exp_name);
        }
    }
}

/// @brief Verifies that BindingVariableMgr::configure() clears the
/// cache first.
TEST(BindingVariableMgrTest, clearOnConfigure) {
    std::string cfg1 =
        R"({"binding-variables":[
            {
                "name": "one",
                "expression": "pkt4.mac",
                "source": "query"
            },
            {
                "name": "two",
                "expression": "pkt4.mac",
                "source": "response"
            } ]})";

    std::string cfg2 =
        R"({"binding-variables":[
            {
                "name": "three",
                "expression": "pkt4.mac",
                "source": "query"
            },
            {
                "name": "four",
                "expression": "pkt4.mac",
                "source": "response"
            } ]})";

    BindingVariableMgrPtr mgr;
    ASSERT_NO_THROW_LOG(mgr.reset(new BindingVariableMgr(AF_INET)));

    ConstElementPtr config;
    ASSERT_NO_THROW_LOG(config = Element::fromJSON(cfg1));
    ASSERT_NO_THROW_LOG(mgr->configure(config));
    auto cache = mgr->getCache();
    ASSERT_TRUE(cache);
    ASSERT_EQ(cache->size(), 2);
    ASSERT_TRUE(cache->getByName("one"));
    ASSERT_TRUE(cache->getByName("two"));

    ASSERT_NO_THROW_LOG(config = Element::fromJSON(cfg2));
    ASSERT_NO_THROW_LOG(mgr->configure(config));
    cache = mgr->getCache();
    ASSERT_TRUE(cache);
    ASSERT_EQ(cache->size(), 2);
    ASSERT_FALSE(cache->getByName("one"));
    ASSERT_FALSE(cache->getByName("two"));
    ASSERT_TRUE(cache->getByName("three"));
    ASSERT_TRUE(cache->getByName("four"));
}

/// @brief Tests BindingVariableMgr::configure() with invalid
/// configuration scenarios.
TEST(BindingVariableMgrTest, invalidConfigure) {
    struct Scenario {
        uint32_t line_;
        uint32_t family_;
        std::string config_;
        std::string expected_error_;
    };

    std::list<Scenario> scenarios = {
    {
        __LINE__,
        AF_INET,
        R"({"binding-variables": "bogus"})",
        "'binding-variables' must be a list"
    },{
        __LINE__,
        AF_INET,
        R"({"binding-variables":[
            {
                "name": "",
                "expression": "pkt4.mac",
                "source": "query"
            } ]})",
        "cannot add BindingVariable to cache: invalid config:"
        " BindingVariable - name cannot be empty"
    }};

    for (auto const& scenario : scenarios) {
        SCOPED_LINE(scenario.line_);
        BindingVariableMgrPtr mgr;
        ASSERT_NO_THROW_LOG(mgr.reset(new BindingVariableMgr(scenario.family_)));
        ConstElementPtr config;
        ASSERT_NO_THROW_LOG(config = Element::fromJSON(scenario.config_));
        ASSERT_THROW_MSG(mgr->configure(config), DhcpConfigError,
                         scenario.expected_error_);
        auto cache = mgr->getCache();
        ASSERT_TRUE(cache);
        EXPECT_EQ(cache->size(), 0);
    }
}

/// @brief Tests BindingVariableMgr::evaluateVariables() for V4 scenarios.
TEST(BindingVariableMgrTest, evaluateVariables4) {
    struct Scenario {
        uint32_t line_;
        std::string config_;
        std::string orig_context_;
        std::string exp_context_;
    };

    std::list<Scenario> scenarios = {
    {
        // No variables configured, nothing in lease context.
        __LINE__,
        R"({})",
        R"({})",
        R"({})"
    },{
        // lease context has no binding-variables, two configured
        __LINE__,
        R"^({"binding-variables":[
            {
                "name": "hwaddr",
                "expression": "hexstring(pkt4.mac,':')",
                "source": "query"
            },
            {
                "name": "yiaddr",
                "expression": "addrtotext(pkt4.yiaddr)",
                "source": "response"
            }]})^",
        R"({})",
        R"({"ISC":{
            "binding-variables":{
                "hwaddr": "01:02:03:04:05:06",
                "yiaddr": "192.0.1.1"
            }
        }})",
    },
    {
        // lease context has binding-variables, none configured
        // Current logic leaves lease untouched.
        __LINE__,
        R"({})",
        R"({"ISC":{
            "binding-variables":{
                "hwaddr": "01:02:03:04:05:06",
                "yiaddr": "192.0.1.1"
            }
        }})",
        R"({"ISC":{
            "binding-variables":{
                "hwaddr": "01:02:03:04:05:06",
                "yiaddr": "192.0.1.1"
            }
        }})",
    },
    {
        // Evaluated variable value is an empty string.
        __LINE__,
        R"^({"binding-variables":[
            {
                "name": "hwaddr",
                "expression": "''",
                "source": "query"
            }]})^",
        R"({"ISC":{
            "binding-variables":{
                "hwaddr": "01:02:03:04:05:06"
            }
        }})",
        R"({"ISC":{
            "binding-variables":{
                "hwaddr": ""
            }
        }})",
    }};

    // Create packet pair and lease.
    Pkt4Ptr query(new Pkt4(DHCPDISCOVER, 1234));
    query->setHWAddr(1, 6, { 0x01, 0x02, 0x03, 0x04, 0x05, 0x06 });

    Pkt4Ptr response(new Pkt4(DHCPOFFER, 1234));
    IOAddress yiaddr("192.0.1.1");
    response->setYiaddr(yiaddr);

    Lease4Ptr lease(new Lease4());

    // Iterate over scenarios.
    for (auto const& scenario : scenarios) {
        SCOPED_LINE(scenario.line_);

        // Create and configure the manager.
        BindingVariableMgrPtr mgr;
        ASSERT_NO_THROW_LOG(mgr.reset(new BindingVariableMgr(AF_INET)));
        ConstElementPtr config;
        ASSERT_NO_THROW_LOG(config = Element::fromJSON(scenario.config_));
        ASSERT_NO_THROW_LOG(mgr->configure(config));

        // Set the lease context to its original content.
        ConstElementPtr orig_context;
        ASSERT_NO_THROW_LOG(orig_context = Element::fromJSON(scenario.orig_context_));
        lease->setContext(orig_context);

        ConstElementPtr exp_context;
        ASSERT_NO_THROW_LOG(exp_context = Element::fromJSON(scenario.exp_context_));

        // Evaluate the variables.
        bool changed;
        ASSERT_NO_THROW_LOG(changed = mgr->evaluateVariables(query, response, lease));

        // If the original and expected lease contexts the same the lease should
        // not have been changed, otherwise its context should have been updated.
        if (*orig_context == *exp_context) {
            ASSERT_FALSE(changed);
            ASSERT_EQ(*lease->getContext(), *orig_context);
        } else {
            ASSERT_TRUE(changed);
            ASSERT_EQ(*lease->getContext(), *exp_context);
        }
    }
}

/// @brief Tests BindingVariableMgr::evaluateVariables() for V6 scenarios.
TEST(BindingVariableMgrTest, evaluateVariables6) {
    struct Scenario {
        uint32_t line_;
        std::string config_;
        std::string orig_context_;
        std::string exp_context_;
    };

    std::list<Scenario> scenarios = {
    {
        // No variables configured, nothing in lease context.
        __LINE__,
        R"({})",
        R"({})",
        R"({})"
    },
    {
        // lease context has no binding-variables, two configured
        __LINE__,
        R"^({"binding-variables":[
            {
                "name": "client-id",
                "expression": "hexstring(option[1].hex,':')",
                "source": "query"
            },
            {
                "name": "transid",
                "expression": "uint32totext(pkt6.transid)",
                "source": "response"
            }]})^",
        R"({})",
        R"({"ISC":{
            "binding-variables":{
                "client-id": "05:06:07:08",
                "transid": "4321"
            }
        }})",
    },
    {
        // lease context has binding-variables, none configured
        // Current logic leaves lease untouched.
        __LINE__,
        R"({})",
        R"({"ISC":{
            "binding-variables":{
                "client-id": "05:06:07:08",
                "transid": "4321"
            }
        }})",
        R"({"ISC":{
            "binding-variables":{
                "client-id": "05:06:07:08",
                "transid": "4321"
            }
        }})",
    },
    {
        // Evaluated variable value is an empty string.
        __LINE__,
        R"^({"binding-variables":[
            {
                "name": "client-id",
                "expression": "''",
                "source": "query"
            }]})^",
        R"({"ISC":{
            "binding-variables":{
                "client-id": "05:06:07:08"
            }
        }})",
        R"({"ISC":{
            "binding-variables":{
                "client-id": ""
            }
        }})",
    }};

    // Create packet pair and lease.
    Pkt6Ptr query(new Pkt6(DHCPV6_SOLICIT, 1234));
    query->addOption(OptionPtr(new Option(Option::V6,
                                          D6O_CLIENTID,
                                          { 0x05, 0x06, 0x07, 0x08 })));

    Pkt6Ptr response(new Pkt6(DHCPV6_ADVERTISE, 4321));
    Lease6Ptr lease(new Lease6());

    // Iterate over scenarios.
    for (auto const& scenario : scenarios) {
        SCOPED_LINE(scenario.line_);

        // Create and configure the manager.
        BindingVariableMgrPtr mgr;
        ASSERT_NO_THROW_LOG(mgr.reset(new BindingVariableMgr(AF_INET6)));
        ConstElementPtr config;
        ASSERT_NO_THROW_LOG(config = Element::fromJSON(scenario.config_));
        ASSERT_NO_THROW_LOG(mgr->configure(config));

        // Set the lease context to its original content.
        ConstElementPtr orig_context;
        ASSERT_NO_THROW_LOG(orig_context = Element::fromJSON(scenario.orig_context_));
        lease->setContext(orig_context);

        ConstElementPtr exp_context;
        ASSERT_NO_THROW_LOG(exp_context = Element::fromJSON(scenario.exp_context_));

        // Evaluate the variables.
        bool changed;
        ASSERT_NO_THROW_LOG(changed = mgr->evaluateVariables(query, response, lease));

        // If the original and expected lease contexts the same the lease should
        // not have been changed, otherwise its context should have been updated.
        if (*orig_context == *exp_context) {
            ASSERT_FALSE(changed);
            ASSERT_EQ(*lease->getContext(), *orig_context);
        } else {
            ASSERT_TRUE(changed);
            ASSERT_EQ(*lease->getContext(), *exp_context);
        }
    }
}

} // end of anonymous namespace