#106: tests: aircox_streamer (#110)

- Writes tests for aircox streamer application;
- Add test utilities in aircox

Co-authored-by: bkfox <thomas bkfox net>
Reviewed-on: rc/aircox#110

aircox_streamer/controllers/streamers.py

@@ -0,0 +1,62 @@
+from django.utils import timezone as tz
+
+from aircox.models import Station
+from .streamer import Streamer
+
+__all__ = ("Streamers",)
+
+
+class Streamers:
+    """Keep multiple streamers in memory, allow fetching informations."""
+
+    streamers = None
+    """Stations by station id."""
+    streamer_class = Streamer
+    timeout = None
+    """Timedelta to next update."""
+    next_date = None
+    """Next update datetime."""
+
+    def __init__(self, timeout=None, streamer_class=streamer_class):
+        self.timeout = timeout or tz.timedelta(seconds=2)
+
+    def reset(self, stations=Station.objects.active()):
+        # FIXME: cf. TODO in aircox.controllers about model updates
+        stations = stations.all()
+        self.streamers = {
+            station.pk: self.streamer_class(station) for station in stations
+        }
+
+    def fetch(self):
+        """Call streamers fetch if timed-out."""
+        if self.streamers is None:
+            self.reset()
+
+        now = tz.now()
+        if self.next_date is not None and now < self.next_date:
+            return
+
+        for streamer in self.streamers.values():
+            streamer.fetch()
+        self.next_date = now + self.timeout
+
+    def get(self, key, default=None):
+        return self.streamers.get(key, default)
+
+    def values(self):
+        return self.streamers.values()
+
+    def __len__(self):
+        return self.streamers and len(self.streamers) or 0
+
+    def __getitem__(self, key):
+        return self.streamers[key]
+
+    def __contains__(self, key):
+        """Key can be a Station or a Station id."""
+        if isinstance(key, Station):
+            return key.pk in self.streamers
+        return key in self.streamers
+
+    def __iter__(self):
+        return self.streamers.values() if self.streamers else iter(tuple())