fix #707: duration stat error in multiple testsuites

Thanks @lijuelijue and @plmmilove

CHANGELOG.md

@@ -15,6 +15,10 @@
 - log httprunner version before running tests
 - remove unused import & code
 
+**Fixed**
+
+- fix #707: duration stat error in multiple testsuites
+
 ## 2.2.6 (2019-09-18)
 
 **Added**

httprunner/report.py

@@ -80,10 +80,16 @@ def aggregate_stat(origin_stat, new_stat):
     for key in new_stat:
         if key not in origin_stat:
             origin_stat[key] = new_stat[key]
+
+        elif key == "duration":
+            # duration = max_end_time - min_start_time
+            max_end_time = max(origin_stat["start_at"] + origin_stat["duration"],
+                               new_stat["start_at"] + new_stat["duration"])
+            min_start_time = min(origin_stat["start_at"], new_stat["start_at"])
+            origin_stat["duration"] = max_end_time - min_start_time
         elif key == "start_at":
-            # start datetime , duration=current_time - min(stat_at)
-            origin_stat[key] = min(origin_stat[key], new_stat[key])
-            origin_stat["duration"] = time.time() - origin_stat[key]
+            # start datetime
+            origin_stat["start_at"] = min(origin_stat["start_at"], new_stat["start_at"])
         else:
             origin_stat[key] += new_stat[key]