https://travis-ci.org/github/bitcoin/bitcoin/jobs/679885530#L8791
virtual RBFTransactionState isRBFOptIn(const CTransaction& tx) = 0;
    
    virtual bool hasDescendantsInMempool(const uint256& txid) = 0;
    
    
    
    virtual bool broadcastTransaction(const CTransactionRef& tx,
        const CAmount& max_tx_fee,
        bool relay,
        std::string& err_string) = 0;
    
    virtual void getTransactionAncestry(const uint256& txid, size_t& ancestors, size_t& descendants) = 0;
    
    
    
    virtual void getPackageLimits(unsigned int& limit_ancestor_count, unsigned int& limit_descendant_count) = 0;
    
    virtual bool checkChainLimits(const CTransactionRef& tx) = 0;
    
    virtual CFeeRate estimateSmartFee(int num_blocks, bool conservative, FeeCalculation* calc = nullptr) = 0;
    
    virtual unsigned int estimateMaxBlocks() = 0;
    
    virtual CFeeRate mempoolMinFee() = 0;
    
    virtual CFeeRate relayMinFee() = 0;
    
    virtual CFeeRate relayIncrementalFee() = 0;