Observer¶

Exercise ¶

Now that we have implemented several iterations of, for example, Adapter, Exercise: Proxy (Rounding Thermometer), etc., driven by tests, lets implement yet another pattern in the same way.

/trainings/material/soup/cxx-code/design-patterns-observer/tests/observer-suite-register-one.cpp¶

#include <gtest/gtest.h>

#include <social-db-observable.h>

namespace {

class MyObserver : public SocialDB_Observable::NewCitizenObserver
{
public:
    const std::string& new_citizen() const
    {
        return _new_citizen_svnr;
    }

    void new_citizen_added(const std::string& svnr) override
    {
        _new_citizen_svnr = svnr;
    }

private:
    std::string _new_citizen_svnr;
};

}

TEST(observer_suite, register_one)
{
    SocialDB_Observable db;

    MyObserver observer;
    db.register_new_citizen_notification(&observer);

    db.insert("1037190666", "Joerg", "Faschingbauer");

    ASSERT_EQ(observer.new_citizen(), "1037190666");
}

/trainings/material/soup/cxx-code/design-patterns-observer/tests/observer-suite-register-many.cpp¶

#include <gtest/gtest.h>

#include <social-db-observable.h>

namespace {

class MyObserver : public SocialDB_Observable::NewCitizenObserver
{
public:
    const std::string& new_citizen() const
    {
        return _new_citizen_svnr;
    }

    void new_citizen_added(const std::string& svnr) override
    {
        _new_citizen_svnr = svnr;
    }

private:
    std::string _new_citizen_svnr;
};

}

TEST(observer_suite, register_many)
{
    SocialDB_Observable db;

    MyObserver observer1;
    MyObserver observer2;

    db.register_new_citizen_notification(&observer1);
    db.register_new_citizen_notification(&observer2);

    db.insert("1037190666", "Joerg", "Faschingbauer");

    ASSERT_EQ(observer1.new_citizen(), "1037190666");
    ASSERT_EQ(observer2.new_citizen(), "1037190666");
}

/trainings/material/soup/cxx-code/design-patterns-observer/tests/observer-suite-register-duplicate.cpp¶

#include <gtest/gtest.h>

#include <social-db-observable.h>

namespace {

class MyObserver : public SocialDB_Observable::NewCitizenObserver
{
public:
    void new_citizen_added(const std::string&) override {}
};

}

TEST(observer_suite, register_duplicate)
{
    SocialDB_Observable db;

    MyObserver observer;
    db.register_new_citizen_notification(&observer);

    try {
        db.register_new_citizen_notification(&observer);
        FAIL();
    }
    catch (const SocialDB_Observable::ObserverAlreadyRegistered&) {}

    // -Werror=restrict
    // ASSERT_THROW(db.register_new_citizen_notification(&observer), SocialDB_Observable::ObserverAlreadyRegistered);
}

/trainings/material/soup/cxx-code/design-patterns-observer/tests/observer-suite-unregister.cpp¶

#include <gtest/gtest.h>

#include <social-db-observable.h>

namespace {

class MyObserver : public SocialDB_Observable::NewCitizenObserver
{
public:
    const std::string& new_citizen() const
    {
        return _new_citizen_svnr;
    }
    void reset()
    {
        _new_citizen_svnr.clear();
    }

    void new_citizen_added(const std::string& svnr) override
    {
        _new_citizen_svnr = svnr;
    }

private:
    std::string _new_citizen_svnr;
};

}

TEST(observer_suite, unregister)
{
    SocialDB_Observable db;

    MyObserver observer;
    db.register_new_citizen_notification(&observer);

    db.insert("1037190666", "Joerg", "Faschingbauer");
    ASSERT_EQ(observer.new_citizen(), "1037190666");

    observer.reset();
    db.unregister_new_citizen_notification(&observer);

    db.insert("1234250497", "Caro", "Faschingbauer");
    
    ASSERT_EQ(observer.new_citizen().size(), 0);
}

/trainings/material/soup/cxx-code/design-patterns-observer/tests/observer-suite-unregister-not-registered.cpp¶

#include <gtest/gtest.h>

#include <social-db-observable.h>

namespace {

class MyObserver : public SocialDB_Observable::NewCitizenObserver
{
public:
    void new_citizen_added(const std::string& svnr) override {}
};

}

TEST(observer_suite, unregister_not_registered)
{
    SocialDB_Observable db;
    MyObserver observer;

    try {
        db.unregister_new_citizen_notification(&observer);
        FAIL();
    }
    catch (const SocialDB_Observable::ObserverNotRegistered&) {}

    // -Werror=restrict
    // ASSERT_THROW(db.unregister_new_citizen_notification(&observer), SocialDB_Observable::ObserverNotRegistered);
}

Observer¶

Exercise¶

Exercise ¶