Coverage for app/backend/src/tests/test_profiling.py: 100%

1import pyroscope 

2import pytest 

3 

4from couchers import profiling 

5from couchers.config import config 

6 

7TAGS = {"role": "api", "instance": "api-1761"} 

8 

9 

10@pytest.fixture 

11def fake_agent(monkeypatch): 

12 """Replace the native pyroscope agent with recorders and reset the per-process agent state.""" 

13 configure_calls: list[dict[str, object]] = [] 

14 shutdown_calls: list[None] = [] 

15 monkeypatch.setattr(pyroscope, "configure", lambda **kw: configure_calls.append(kw)) 

16 monkeypatch.setattr(pyroscope, "shutdown", lambda: shutdown_calls.append(None)) 

17 monkeypatch.setattr(profiling, "_tags", TAGS) 

18 monkeypatch.setattr(profiling, "_running", False) 

19 monkeypatch.setattr(profiling, "_sample_rate", None) 

20 monkeypatch.setattr(profiling, "_oncpu", None) 

21 monkeypatch.setitem(config, "PYROSCOPE_SERVER", "https://localhost") 

22 monkeypatch.setitem(config, "PYROSCOPE_AUTH_TOKEN", "token") 

23 return configure_calls, shutdown_calls 

24 

25 

26def _enable(feature_flags, *, rate=20, mode="wall"): 

27 feature_flags.set("profiling_enabled", True) 

28 feature_flags.set("profiling_sample_rate", rate) 

29 feature_flags.set("profiling_mode", mode) 

30 

31 

32def test_disabled_does_nothing(feature_flags, fake_agent): 

33 configure_calls, shutdown_calls = fake_agent 

34 feature_flags.set("profiling_enabled", False) 

35 profiling._reconcile() 

36 assert configure_calls == [] 

37 assert shutdown_calls == [] 

38 assert profiling._running is False 

39 

40 

41def test_enables_with_flag_driven_params(feature_flags, fake_agent, monkeypatch): 

42 monkeypatch.setitem(config, "PYROSCOPE_SERVER", "https://pyroscope.couchershq.org") 

43 monkeypatch.setitem(config, "PYROSCOPE_AUTH_TOKEN", "secret-token") 

44 configure_calls, _ = fake_agent 

45 _enable(feature_flags, rate=50, mode="cpu") 

46 profiling._reconcile() 

47 

48 assert len(configure_calls) == 1 

49 kw = configure_calls[0] 

50 assert kw["sample_rate"] == 50 

51 assert kw["oncpu"] is True 

52 assert kw["server_address"] == "https://pyroscope.couchershq.org" 

53 assert kw["http_headers"] == {"Authorization": "Bearer secret-token"} 

54 assert kw["tags"] == TAGS 

55 # enable_logging must never be True on a reconfigure (re-init aborts the process) 

56 assert kw["enable_logging"] is False 

57 assert (profiling._running, profiling._sample_rate, profiling._oncpu) == (True, 50, True) 

58 

59 

60def test_idempotent_when_unchanged(feature_flags, fake_agent): 

61 configure_calls, shutdown_calls = fake_agent 

62 _enable(feature_flags) 

63 profiling._reconcile() 

64 profiling._reconcile() 

65 assert len(configure_calls) == 1 

66 assert shutdown_calls == [] 

67 

68 

69def test_rate_change_restarts_agent(feature_flags, fake_agent): 

70 configure_calls, shutdown_calls = fake_agent 

71 _enable(feature_flags, rate=20) 

72 profiling._reconcile() 

73 feature_flags.set("profiling_sample_rate", 73) 

74 profiling._reconcile() 

75 assert len(configure_calls) == 2 

76 assert len(shutdown_calls) == 1 

77 assert configure_calls[-1]["sample_rate"] == 73 

78 assert profiling._sample_rate == 73 

79 

80 

81def test_mode_change_restarts_agent(feature_flags, fake_agent): 

82 configure_calls, shutdown_calls = fake_agent 

83 _enable(feature_flags, mode="wall") 

84 profiling._reconcile() 

85 feature_flags.set("profiling_mode", "cpu") 

86 profiling._reconcile() 

87 assert len(shutdown_calls) == 1 

88 assert configure_calls[-1]["oncpu"] is True 

89 assert profiling._oncpu is True 

90 

91 

92def test_disable_after_running_shuts_down(feature_flags, fake_agent): 

93 _, shutdown_calls = fake_agent 

94 _enable(feature_flags) 

95 profiling._reconcile() 

96 feature_flags.set("profiling_enabled", False) 

97 profiling._reconcile() 

98 assert len(shutdown_calls) == 1 

99 assert profiling._running is False 

100 

101 

102def test_sample_rate_is_clamped(feature_flags, fake_agent): 

103 configure_calls, _ = fake_agent 

104 _enable(feature_flags, rate=100000) 

105 profiling._reconcile() 

106 assert configure_calls[0]["sample_rate"] == 250