Adding test for load historic candles

Author: kylewidmann

pytrade/broker.py

@@ -52,7 +52,7 @@ def load_instrument_candles(
         if key in self._subscriptions:
             raise RuntimeError(
                 f"Consumers are already subscribed to {instrument}[{granularity.value}], \
-                    can not populate historical data."
+can not populate historical data."
             )
 
         instrument_data = self._data_context.get(instrument, granularity)

tests/unit/test_broker.py

@@ -2,6 +2,8 @@
 from datetime import datetime, timedelta, timezone
 from unittest.mock import MagicMock, Mock
 
+import pytest
+
 from pytrade.broker import Broker
 from pytrade.instruments import MINUTES_MAP, Candlestick, FxInstrument, Granularity
 from pytrade.models import Order
@@ -117,3 +119,32 @@ def test_load_instrument_candles():
 
     broker.load_instrument_candles(instrument, granularity, 20)
     assert len(instrument_data.df) == 20
+
+
+def test_load_instrument_candles_after_subscribing():
+    client = MagicMock()
+    client.get_candles.side_effect = _get_candles
+    broker = Broker(client)
+
+    instrument = FxInstrument.EURUSD
+    granularity = Granularity.M1
+
+    assert len(broker._subscriptions) == 0
+    assert client.subscribe.call_count == 0
+
+    broker.subscribe(instrument, granularity)
+
+    assert len(broker._subscriptions) == 1
+    assert client.subscribe.call_count == 1
+    assert len(broker._data_context._data) == 1
+
+    instrument_data = broker._data_context.get(instrument, granularity)
+    assert len(instrument_data.df) == 0
+
+    with pytest.raises(RuntimeError) as e:
+        broker.load_instrument_candles(instrument, granularity, 10)
+
+    assert (
+        e.value.args[0]
+        == "Consumers are already subscribed to FxInstrument.EURUSD[M1], can not populate historical data."
+    )