Semiconductor memory device having an open bit line structure, and method of testing the same

A memory core having an open bit line structure and a semiconductor memory device having the memory core includes an edge sub-array and a dummy bit line control circuit. The edge sub-array has a plurality of word lines, a plurality of bit lines and a plurality of dummy bit lines. The dummy bit line control circuit amplifies and latches voltage signals of the dummy bit lines in a test sensing mode. Accordingly, the semiconductor memory device having the memory core may test defects of the edge sub-array included in the memory core.