1. A test method including: measuring a quiescent power supply current for each test vector switched among a plurality of test vectors, for each of a plurality of samples of a device under test; calculating a statistical quiescent power supply current for each test vector, and creating first array data including identifiers for the test vectors and the statistical quiescent power supply current values as elements; sorting the first array data using the statistical quiescent power supply current value as a key so as to create second array data; calculating the difference in statistical quiescent power supply current, which is obtained by calculating the differences between the adjacent statistical quiescent power supply current elements of the second array data, so as to create third array data including the identifiers for the test vectors and the differences in current value as elements; and sorting the third array data using the difference in current value as a key so as to create fourth array data, wherein the test method further comprises, measuring a quiescent power supply current for each test vector switched among a plurality of test vectors, for a quality evaluation target device under test, so as to create fifth array data including the identifiers for the test vectors and the quiescent power supply current values as elements; sorting the fifth array data such that the order of the identifiers for the test vectors thereof matches the order of the identifiers for the test vectors included in the second array data thereby creating sixth array data; calculating the difference in quiescent power supply current, which is obtained by calculating the differences between the adjacent quiescent power supply current elements of the sixth array data, so as to create seventh array data including the identifiers for the test vectors and the differences in current value as elements; sorting the seventh array data such that the order of the identifiers for the test vectors thereof matches the order of the identifiers for the test vectors included in the fourth array data; and assessing the quality of the quality evaluation target device under test, based upon the eighth array data.