Initial commit

yksa_orbital/tests/test_model_config.py

@@ -0,0 +1,74 @@
+from __future__ import annotations
+
+import pytest
+from django.core.cache import cache
+
+from odm import PropagationError
+from yksa_orbital import model_config as mc
+
+
+@pytest.fixture(autouse=True)
+def _clear_cache():
+    cache.delete(mc.CACHE_KEY)
+    yield
+    cache.delete(mc.CACHE_KEY)
+
+
+class _Backend:
+    def __init__(self, result=None, error=None):
+        self.result = result
+        self.error = error
+        self.calls = 0
+
+    def model_config(self):
+        self.calls += 1
+        if self.error:
+            raise self.error
+        return self.result
+
+
+def test_the_model_is_read_once_and_cached(monkeypatch):
+    backend = _Backend({"decay": {"altitude_km": 105.0}})
+    monkeypatch.setattr(mc, "get_backend", lambda name=None: backend)
+
+    assert mc.model_config()["decay"]["altitude_km"] == 105.0
+    mc.model_config()
+    assert backend.calls == 1
+
+
+def test_an_unreachable_sidecar_falls_back_without_raising(monkeypatch):
+    backend = _Backend(error=PropagationError("unreachable"))
+    monkeypatch.setattr(mc, "get_backend", lambda name=None: backend)
+
+    assert mc.model_config()["unavailable"] is True
+
+
+def test_the_failure_is_cached_too(monkeypatch):
+    """Otherwise a sidecar that is down costs a connection attempt on every page
+    render -- and against an unresolvable hostname each one is a DNS timeout, so
+    a caption takes the page down instead of degrading."""
+    backend = _Backend(error=PropagationError("unreachable"))
+    monkeypatch.setattr(mc, "get_backend", lambda name=None: backend)
+
+    mc.model_config()
+    mc.model_config()
+    mc.model_config()
+    assert backend.calls == 1
+
+
+def test_a_local_override_wins_over_the_sidecar(monkeypatch, settings):
+    """When this deployment overrides a knob it really is flying something else,
+    and a caption reading the sidecar's value would describe a different run."""
+    backend = _Backend({"decay": {"altitude_km": 105.0}})
+    monkeypatch.setattr(mc, "get_backend", lambda name=None: backend)
+    settings.DECAY_ALTITUDE_KM = 120.0
+
+    assert mc.setting("decay", "altitude_km") == 120.0
+
+
+def test_an_unset_override_reads_the_sidecar(monkeypatch, settings):
+    backend = _Backend({"decay": {"altitude_km": 105.0}})
+    monkeypatch.setattr(mc, "get_backend", lambda name=None: backend)
+    settings.DECAY_ALTITUDE_KM = None
+
+    assert mc.setting("decay", "altitude_km") == 105.0