PooCon2016: Testing and debugging Pootle

Testing with pootle

• Coverage is up to around 93%
• py.test
• High test coverage facilitates rapid dev
• Machine linting
• Some doctests

Linting tools

• flake8 - combined pycodestyle (was pep8) and pyflakes
• pylint
• csslint
• eslint
• isort
• Commands:

make lint-python
make lint-css
make lint-js

CI tools

• travis.com
• coveralls.io
• codecov.io
• landscape.io
• requires.io
• New Relic

Introduction to pdb

• Swiss army knife of debugging
• Introspect local vars and test code
• import pdb; pdb.set_trace()
• import inspect; inspect.stack()[10]
• https://github.com/translate/pootle/wiki/Debugging-with-pdb

SQL debugging

• Usually the most important part of optimization
• Debug lines of django code with debug_sql
  • https://github.com/translate/pootle/wiki/Debugging-sql
• Use the SQL in dbshell and experiment
  • describe select ...
  • show create table ...
  • alter table ... add index ...

Debugging tests and optimizing

• py.test -vv --debug.tests my-timings.txt
• Drill down to time-consuming tests and debug_sql
• Common optimizations
  • preventing duplicate calls
  • adding select_related or pre-initializing related objects
  • prefetching
  • values_list - sometimes with a ProxyAdapter (also Queryset.only() ?)
  • iterator
  • combining SQL
  • splitting SQL

Debugging views

• We have a simple bit of middle-ware to debug log view SQL and provide timings

The test environment

• pytest_pootle.env
• project0, language0, tp0, store0, vfolder0
• Default users - admin, system, default, member, member2
• Matrix of translation projects, stores, units, suggestions, submissions