4.3. Debugging

• the relationship between debugging and testing

  • reason for debugging: trying to pin down the root cause of unwanted/unexpected behaviour

  • reason for testing: specifying the expected behaviour in form of executable code (i.e. tests)

• read the error messages of the Python interpreter

  • Most problems can be solved carefully reading the error messages

  • usual problem: RTFM

• poor man’s debugging: print statements

  • short-term strategy

  • not advocating using print statements instead of a debugger, but rather admitting what most people seem to do

  • tips and tricks how to use it sensibly (finding a lost print statement can be tedious)

• convert bugs into tests

  • see next section on tests and testing for details

• use the builtin Python debugger pdb

  • admittedly, I have never used it myself

  • see the official documentation for details