Our CSVModel code is fairly self-contained apart from its need to read and write files. Since file operations are one of the more common things that need to be mocked out in a test, the mock module provides mock_open, a Mock subclass ready-made to replace Python's open method. When called, a mock_open object returns a mock file handle object, complete with support for the read(), write(), and readlines() methods.
Let's begin creating our test case class in test/test_models.py as follows:
from .. import modelsfrom unittest import TestCasefrom unittest import mockclass TestCSVModel(TestCase): def setUp(self): self.file1_open = mock.mock_open( read_data=( "Date,Time,Technician,Lab,Plot,Seed sample,Humidity,Light," "Temperature,Equipment ...
