Testing interactions approach 1 - no mocking

Siddharta Govindaraj · Siddharta Govindaraj · commit 3853694f98ae · 2015-03-23T15:07:03.000+05:30
diff --git a/stock_alerter/alert.py b/stock_alerter/alert.py
@@ -0,0 +1,18 @@
+class Alert:
+    """Maps a Rule to an Action, and triggers the action if the rule
+    matches on any stock update"""
+
+    def __init__(self, description, rule, action):
+        self.description = description
+        self.rule = rule
+        self.action = action
+
+    def connect(self, exchange):
+        self.exchange = exchange
+        dependent_stocks = self.rule.depends_on()
+        for stock in dependent_stocks:
+            exchange[stock].updated.connect(self.check_rule)
+
+    def check_rule(self, stock):
+        if self.rule.matches(self.exchange):
+            self.action.execute(self.description)
diff --git a/stock_alerter/tests/test_alert.py b/stock_alerter/tests/test_alert.py
@@ -0,0 +1,24 @@
+import unittest
+from datetime import datetime
+
+from ..alert import Alert
+from ..rule import PriceRule
+from ..stock import Stock
+
+
+class TestAction:
+    executed = False
+
+    def execute(self, description):
+        self.executed = True
+
+
+class AlertTest(unittest.TestCase):
+    def test_action_is_executed_when_rule_matches(self):
+        exchange = {"GOOG": Stock("GOOG")}
+        rule = PriceRule("GOOG", lambda stock: stock.price > 10)
+        action = TestAction()
+        alert = Alert("sample alert", rule, action)
+        alert.connect(exchange)
+        exchange["GOOG"].update(datetime(2014, 2, 10), 11)
+        self.assertTrue(action.executed)
