TDD python ne-april-2014
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TDD involves writing tests before code to verify functionality. The process is: 1. Write a test that fails without the target code implemented. 2. Write the minimum code required for the test to pass. 3. Refactor the code as needed to improve design while ensuring tests still pass. The goal is to use tests to drive code development and prevent regressions, with tests providing feedback on potential design issues. TDD encourages writing code in small, testable units and helps developers learn through practice.
![–codebetter.com
“Unit Tests confirm we have written the code
right [sic].
Acceptance Tests that we built the right
software.”](https://image.slidesharecdn.com/tdd-pythonne-april-2014-150809121900-lva1-app6892/85/TDD-python-ne-april-2014-22-320.jpg)
TDD python ne-april-2014
- 1. TDD* Alex Kavanagh @ajkavanagh *Test Driven Development
- 2. Why?
- 3. –Michael Sinz “Programming is like sex … one mistake and you have to support it for the rest of your life.”
- 4. –Steve M. McConnell “The problem with quick and dirty is that Dirty remains long after the quick has been forgotten.”
- 5. –John Woods “Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live.”
- 6. What is TDD?
- 9. Write Test
- 10. Run the test and see it fail $ nosetests -v websandpym/tests/test_auth_utils.py:Utils_Tests.test__generate_jti_claim test__generate_jti_claim (websandpym.tests.test_auth_utils.Utils_Tests) ... ERROR ====================================================================== ERROR: test__generate_jti_claim (websandpym.tests.test_auth_utils.Utils_Tests) ---------------------------------------------------------------------- Traceback (most recent call last): File "/Users/alex/unison-root/Projects/Websand/instances/websand-pym/websand-pym/websandpym/tests/test_auth_utils.py", line 101, in test__generate_jti_claim claims = auth_utils._generate_jti_claim() nose.proxy.AttributeError: 'module' object has no attribute '_generate_jti_claim' -------------------- >> begin captured logging << -------------------- passlib.utils.compat: DEBUG: loaded lazy attr 'SafeConfigParser': <class 'configparser.ConfigParser'> passlib.utils.compat: DEBUG: loaded lazy attr 'NativeStringIO': <class '_io.StringIO'> passlib.utils.compat: DEBUG: loaded lazy attr 'BytesIO': <class '_io.BytesIO'> passlib.registry: DEBUG: registered 'bcrypt' handler: <class 'passlib.handlers.bcrypt.bcrypt'> passlib.registry: DEBUG: registered 'pbkdf2_sha256' handler: <class 'passlib.handlers.pbkdf2.pbkdf2_sha256'> --------------------- >> end captured logging << --------------------- ---------------------------------------------------------------------- Ran 1 test in 0.002s FAILED (errors=1)
- 11. Write some code
- 12. Run test again $ nosetests -v websandpym/tests/test_auth_utils.py:Utils_Tests.test__generate_jti_claim test__generate_jti_claim (websandpym.tests.test_auth_utils.Utils_Tests) ... ok ---------------------------------------------------------------------- Ran 1 test in 0.014s OK
- 13. …until the test passes
- 14. then …
- 15. Refactor
- 17. In summary
- 19. TDD and Python Learning by doing … (scary live demo) (to play along: https://github.com/ajkavanagh/PythonNE-TDD-Example)
- 21. Topics to look at Mocking End2End Testing (for web frameworks) BDD etc. (it’s a big field …)
- 22. –codebetter.com “Unit Tests confirm we have written the code right [sic]. Acceptance Tests that we built the right software.”
- 23. –Kent Beck “TDD doesn’t drive good design. TDD gives you immediate feedback about what is likely to be bad design.”
- 24. Code Dojo Ideas 1. Write a module that ‘manages’ Polar coords. Allow transformations between cartesian and polar coords. 2. Write a module that counts frequencies of words passed to. Extra credit - remember previous counts and add to them. 3. Implement a really simple shopping cart. Extra credit - add a discounting system. 4. Implement a Bank Account class that can transfer money between accounts, have account limits.