This PR adds tests for the Graphite web stdev function, matching the tests implemented for stdev in Graphite web. Note that after implementing this test found in Graphite web's code, an issue was found with the stdev function, where a value of 0 was calculated for the standard deviation if the first value in the series was math.NaN(). This PR also includes a fix that should handle this scenario.
This PR adds tests for the Graphite web stdev function, matching the tests implemented for stdev in Graphite web. Note that after implementing this test found in Graphite web's code, an issue was found with the stdev function, where a value of 0 was calculated for the standard deviation if the first value in the series was math.NaN(). This PR also includes a fix that should handle this scenario.