依存性の注入のテスト

dependency-injection-test.cpp

#include <iostream>
#include <memory>

class IFoo
{
public:
    virtual ~IFoo() {}
    virtual int f() = 0;
};

class Foo : public IFoo
{
public:
    Foo() { std::cout << "Foo ctor" << std::endl; }
    ~Foo() { std::cout << "Foo dtor" << std::endl; }
    
    int f() override
    {
        return 123;
    }
};

class Foo2 : public IFoo
{
public:
    Foo2() { std::cout << "Foo2 ctor" << std::endl; }
    ~Foo2() { std::cout << "Foo2 dtor" << std::endl; }
    
    int f() override
    {
        return 456;
    }
};

class Bar : public IFoo
{
public:
    Bar() : _foo(std::move(std::make_unique<Foo>())) { std::cout << "Bar ctor" << std::endl; }
    
    Bar(std::unique_ptr<IFoo>&& foo) : _foo(std::move(foo)) { std::cout << "Bar ctor2" << std::endl; }
    
    ~Bar() { std::cout << "Bar dtor" << std::endl; }
    
    int f() override
    {
        return _foo->f();
    }
    
private:
    std::unique_ptr<IFoo> _foo;
};

int main()
{
    auto foo = std::make_unique<Bar>();
    std::cout << foo->f() << std::endl;
    
    auto foo2 = std::make_unique<Bar>(std::make_unique<Foo2>());
    std::cout << foo2->f() << std::endl;
    
    return 0;
}