Fix rounding

aqimon/database.py

@@ -122,7 +122,9 @@ async def get_averaged_reads(dbconn: databases.Database, lookback_to: datetime)
     lookback = int(lookback_to.timestamp())
     result = await dbconn.fetch_one(
         "SELECT "
-        "AVG(pm25) as avg_pm25, AVG(pm10) as avg_pm10, COUNT(*) as count, MIN(event_time) as oldest_time "
+        "ROUND(AVG(pm25), 2) as avg_pm25, ROUND(AVG(pm10), 2) as avg_pm10, "
+        "COUNT(*) as count, "
+        "MIN(event_time) as oldest_time "
         "FROM read_log "
         "WHERE (event_time >= :lookback) OR "
         "(event_time = (SELECT MAX(event_time) FROM read_log WHERE event_time <= :lookback)) ORDER BY event_time ASC",

tests/test_database.py

@@ -207,6 +207,21 @@ async def test_get_averaged_reads(database_conn):
     assert result.oldest_read_time == current_time - timedelta(hours=8)
 
 
+@pytest.mark.asyncio
+async def test_get_averaged_reads_rounding(database_conn):
+    # Add reads every two hours
+    current_time = datetime(2020, 1, 1, 12, 0, 0)
+    lookback_to = current_time - timedelta(hours=8)
+    await database.add_read(database_conn, current_time - timedelta(hours=2), pm10=2, pm25=2)
+    await database.add_read(database_conn, current_time - timedelta(hours=4), pm10=4, pm25=3)
+    await database.add_read(database_conn, current_time - timedelta(hours=6), pm10=4, pm25=3)
+
+    result = await database.get_averaged_reads(database_conn, lookback_to)
+    assert result.count == 3
+    assert result.avg_pm10 == 3.33
+    assert result.avg_pm25 == 2.67
+
+
 @pytest.mark.asyncio
 async def test_get_averaged_reads_looks_past(database_conn):
     current_time = datetime(2020, 1, 1, 12, 0, 0)