How to acces google test fixture static variable

I would like to test one of my classes with google test. The initialization of this class takes a lot of time and resources, so I would like to do it only once for all of my tests cases, so I am trying to use fixture with SetUpTestSuite(). In my fixture I declare a variable:

static MyClassToBeTested my_class;

In my test cases I would like to access the my_class variable.

During compiling I get the following error:

undefined reference to `MyTest::my_class'

In my test cases I tried to access it with simply my_class and also MyTest::my_class.

class MyTest : public ::testing::Test {
protected:
    static MyClassToBeTested my_class;
    static void SetUpTestSuite() {
        //doing some stuff here
    }
};
TEST_F(MyTest, first_test) {
    ASSERT_EQ(my_class.foo(), 5);
}