adding test duration

rowers/utils.py

@@ -377,6 +377,8 @@ def wavg(group, avg_name, weight_name):
         return d.mean()
 
 def totaltime_sec_to_string(totaltime,shorten=False):
+    if np.isnan(totaltime):
+        return ''
     hours = int(totaltime / 3600.)
     if hours > 23:
         message = 'Warning: The workout duration was longer than 23 hours. '