Debug pytest

Stop inside a Python test.

Prerequisites

• debugpy installed into the interpreter that runs your tests:

.venv/bin/pip install debugpy

• pytest in the same environment

The short way: the test under the cursor

:DebugTest

or

bugsaur gui --project . --test-at tests/test_orders.py:24

Bugsaur runs the selected pytest node through debugpy. The adapter, environment and working directory come from the profile.

The buffer must be saved, and saved breakpoints are not picked up — a test run uses only the breakpoints of that request.

The long way: a pytest profile

For running a whole suite or a directory under the debugger:

[profiles.tests]
adapter = "debugpy"
adapter_command = "${root}/.venv/bin/python"
program = "."
args = ["-x", "tests/"]

[profiles.tests.launch_arguments]
module = "pytest"
python = "${root}/.venv/bin/python"

module = "pytest" is the escape hatch: debugpy accepts a module key, and the profile schema has no dedicated field for it.

-x stops on the first failure, which is usually what you want under a debugger.

bugsaur gui --project . --profile tests --break src/orders.py:88

Useful pytest arguments

Argument	Effect
-x	stop after the first failure
-s	do not capture output, so print reaches the Logs panel
-k expr	only tests whose name matches
tests/test_orders.py::test_create	one specific test

args = ["-x", "-s", "tests/test_orders.py::test_create"]

Two interpreters

adapter_command chooses the interpreter that runs the adapter; launch_arguments.python chooses the one that runs your code. They are usually the same venv, and No module named debugpy almost always means one of them is pointing somewhere else.

When it does not work

Symptom	Fix
No module named debugpy	install it into the interpreter in adapter_command
No module named pytest	install pytest into the same environment
Breakpoints in a fixture never fire	the fixture is cached from an earlier test — check the scope
ImportError for your package	working directory — Working directory
print output invisible	add -s