Using utcfromtimestamp to get to_iso time to make sure local timezone doesn't affect datetime value

Author: pandpara

codeguru_profiler_agent/utils/time.py

@@ -3,11 +3,14 @@
 import time
 from datetime import datetime
 
+
 def to_iso(epoch_milli):
     try:
-        return datetime.fromtimestamp(epoch_milli / 1000).isoformat() + "Z"  # ISO 8601 date-time format
+        return datetime.utcfromtimestamp(epoch_milli / 1000).isoformat(
+            timespec='milliseconds') + "Z"  # ISO 8601 date-time format
     except ValueError:
         return str(epoch_milli)
 
+
 def current_milli_time(clock=time.time):
     return int(clock() * 1000)

test/unit/agent_metadata/test_agent_debug_info.py

@@ -20,10 +20,10 @@ def test_it_returns_json_with_error_counts(self):
         }
 
     def test_it_returns_json_with_agent_start_time(self):
-        subject = AgentDebugInfo(agent_start_time=1577869200000)  # 2020-01-01T01:00:00Z
+        subject = AgentDebugInfo(agent_start_time=1577840400000)  # 2020-01-01T01:00:00Z UTC
 
         serialized_json = subject.serialize_to_json()
-        assert serialized_json["agentStartTime"] == "2020-01-01T01:00:00Z"
+        assert serialized_json["agentStartTime"] == "2020-01-01T01:00:00.000Z"
 
     def test_it_returns_json_with_generic_metrics(self):
         timer = Timer()