python study notes - unit test, UnitTest

The so-called unit test is a type of testing that tests the correctness of a module, a function, or a class.

The test-driven development method is called Test Driven Development. This development model is not just testing, but a way to decompose requirements and ensure code quality. means.

#Unit testing not only ensures that the function, module or class meets our needs during testing. At the same time, it will also help us to modify the class or function in the future. We only need to run the unit test again to ensure that our modification will not affect the function.

Of course, unit testing will also greatly increase the amount of code.

Writing unit test code requires the introduction of Python's unittest package. We can create a new unit test class, but this class needs to inherit the unitest.TestCase class. The test method in the test class must start with test, otherwise it will not be executed. Then we can use the methods in unitest.TestCase. Commonly used methods are:

assertEqual(self, first, second) #Judge whether it is the expected value
assertTrue(bool) #Judge whether it is true
assertRaises(exception) #Judge whether it is true or false Throws a specific exception.

Let’s give an example:

We first define a class custom class and then unit test it.

Dict.py

class Dict(dict):
def __init__(self, **kwargs):
super(Dict, self).__init__(**kwargs)
def __getattr__(self, item):
try:
return self[item]
except KeyError:
raise AttributeError
def __setattr__(self, key, value):
self[key] = value
import unittest
from Dict import Dictclass DictTest(unittest.TestCase):
def test_init(self):
d = Dict(a=100, b=200)
self.assertEqual(d.a, 100)
self.assertEqual(d.b, 200)
self.assertTrue(isinstance(d, dict))
def test_key(self):
d = Dict()
d['key'] = "300"
self.assertEqual(d["key"], "300")
def test_attar(self):
d = Dict()
d.attar = "attar"
self.assertTrue("attar" in d)
self.assertEqual(d.attar, "attar")
def test_keyError(self):
d = Dict()
with self.assertRaises(KeyError):
value = d["NotExisted"]
def test_attarError(self):
d = Dict()
with self.assertRaises(AttributeError):
value = d.not_existed
if __name__ == '__main__':
unittest.main()

Because we have defined a subclass of dict, we need to test its key and value; at the same time it is A class, so we also need to test its attributes.

The unittest.TestCase subclass we defined needs to write two sentences:

if __name__ == '__main__':
unittest.main()

We can execute it like a normal python file.

In addition, we can also execute multiple tests in the following way

python -m unittest DictTest
setUp and tearDown functions.

The setUp and tearDown functions are two special functions. setUp runs before all unit tests start; tearDown function runs after all unit tests run. The main application scenarios of these two functions are: for example, when you need to connect to a database, you can start the connection in the setUp function and close the connection in the tearDown function.

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