README.md

AltWalker Example: Python Debugger

A simple example that shows how to use the python debugger with AltWalker.

Read more about the pdb here.

Setup

Linux/MacOS:

$ cd python-debugger
$ python3 -m venv .venv
$ source .venv/bin/activate
$ pip install -r requirements.txt

Windows:

$ cd python-debugger
$ python3 -m venv .venv
$ .venv/Scripts/activate.bat
$ pip install -r requirements.txt

Read more about venv here.

Run the debugger with AltWalker

Because AltWalker redirects the output of your test methods using contextlib.redirect_stdout simply calling breakpoint or pdb.set_trace won't work.

AltWalker will intercept the messages from the debugger and you will not be able to see them.

You will need to initialize a debugger class that will use the default sys.stdout (the one before the redirect) as output and call set_trace on it.

# test.py

import sys
import pdb


debugger = pdb.Pdb(skip=['altwalker.*'], stdout=sys.stdout)


class ExampleModel:

    # ...

	def element_method(self):
		debugger.set_trace()

    # ...

We also set the skip argument, so that the debugger will not step into frames that originate in the altwalker module.

The skip argument, if given, must be an iterable of glob-style module name patterns. The debugger will not step into frames that originate in a module that matches one of these patterns.

• https://docs.python.org/3/library/pdb.html#pdb.Pdb

$ altwalker online tests -m models/debug.json "random(length(100))"

You will see somethig like this:

Running:
[2020-01-17 17:24:06.347541] DebugModel.v_state_a Running
[2020-01-17 17:24:06.347959] DebugModel.v_state_a Status: PASSED

[2020-01-17 17:24:06.364014] DebugModel.e_action_a Running
[2020-01-17 17:24:06.364255] DebugModel.e_action_a Status: PASSED

[2020-01-17 17:24:06.381578] DebugModel.v_state_b Running
[2020-01-17 17:24:06.382283] DebugModel.v_state_b Status: PASSED

[2020-01-17 17:24:06.415607] DebugModel.e_action_b Running
[2020-01-17 17:24:06.416030] DebugModel.e_action_b Status: PASSED

[2020-01-17 17:24:06.434449] DebugModel.v_state_c Running
--Return--
> ../altwalker-examples/python-debugger/tests/test.py(18)v_state_c()->None
-> debugger.set_trace()
(Pdb)

And now you are in inside the debugger.

Models

Note: For this example the model is irrelevant.

• Example Model from models/debug.json