Explain the setUp and tearDown Python methods used in test cases

Question

Can anyone explain the use of Python s setUp and tearDown methods while writing test cases apart from that setUp is called immediately before calling the test method and tearDown is called immediately after it has been called

User · Answer

Suppose you have a suite with 10 tests  8 of the tests share the same setup teardown code  The other 2 don t   setup and teardown give you a nice way to refactor those 8 tests  Now what do you do with the other 2 tests  You d move them to another testcase suite  So using setup and teardown also helps give a natural way to break the tests into cases suites

User · Answer

In general you add all prerequisite steps to setUp and all clean-up steps to tearDown   You can read more with examples here      When a setUp   method is defined  the test runner will run that method   prior to each test  Likewise  if a tearDown   method is defined  the   test runner will invoke that method after each test     For example you have a test that requires items to exist  or certain state - so you put these actions creating object instances  initializing db  preparing rules and so on  into the setUp   Also as you know each test should stop in the place where it was started - this means that we have to restore app state to it s initial state - e g close files  connections  removing newly created items  calling transactions callback and so on - all these steps are to be included into the tearDown   So the idea is that test itself should contain only actions that to be performed on the test object to get the result  while setUp and tearDown are the methods to help you to leave your test code clean and flexible    You can create a setUp and tearDown for a bunch of tests and define them in a parent class - so it would be easy for you to support such tests and update common preparations and clean ups   If you are looking for an easy example please use the following link with example

User · Answer

You can use these to factor out code common to all tests in the test suite   If you have a lot of repeated code in your tests  you can make them shorter by moving this code to setUp tearDown   You might use this for creating test data  e g  setting up fakes mocks   or stubbing out functions with fakes   If you re doing integration testing  you can use check environmental pre-conditions in setUp  and skip the test if something isn t set up properly   For example   class TurretTest unittest TestCase        def setUp self           self turret factory   TurretFactory           self turret   self turret factory CreateTurret        def test turret is on by default self           self assertEquals True  self turret is on         def test turret turns can be turned off self           self turret turn off           self assertEquals False  self turret is on

[python] Explain the "setUp" and "tearDown" Python methods used in test cases

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