How to write unit test for an unordered_map

I am a beginner with cppunit testing framework and have to test an unordered_map. Here is the code for the same:

typedef struct  {
        BDD_ID bdd_id;
        string label;
        BDD_ID top; //string makes it more difficult to be manipulated
        BDD_ID high;
        BDD_ID low;
    }Node;
    unordered_map<BDD_ID, Node> Unique_Table;

In my header file for testing, how do I declare Unique_Table? Thanks in advance!