Mocking the open function

Siddharta Govindaraj · Siddharta Govindaraj · commit 9d466f7bd956 · 2015-03-26T09:05:45.000+05:30
diff --git a/stock_alerter/tests/test_reader.py b/stock_alerter/tests/test_reader.py
@@ -0,0 +1,18 @@
+import unittest
+from unittest import mock
+from datetime import datetime
+
+from ..reader import FileReader
+
+
+class FileReaderTest(unittest.TestCase):
+    @mock.patch("builtins.open",
+                mock.mock_open(read_data="""\
+GOOG,2014-02-11T14:10:22.13,10"""))
+    def test_FileReader_returns_the_file_contents(self):
+        reader = FileReader("stocks.txt")
+        updater = reader.get_updates()
+        update = next(updater)
+        self.assertEqual(("GOOG",
+                          datetime(2014, 2, 11, 14, 10, 22, 130000),
+                          10), update)
