def load_testdata(self):
        p = Path(TEST_DATA_PATH)
        files = [x for x in p.iterdir()
                 if x.is_file() and x.name.endswith('json')]
        for f in files:
            if f.name.startswith("block"):
                height = f.name[6:-5]
                with f.open() as jf:
                    raw_block = json.load(jf)
                    block_hash = raw_block['hash']
                    self.heights[int(height)] = block_hash
                    self.blocks[block_hash] = raw_block
            elif f.name.startswith("tx"):
                tx_hash = f.name[3:-5]
                with f.open() as jf:
                    raw_block = json.load(jf)
                    self.txs[tx_hash] = raw_block