If you want to enter debugging when running pytest in VSCode and stay at a line of code, you could click 'Debug Test' at the top of the method after selecting the pytest test, as shown in the screenshot:

In addition, "python.testing.pytestArgs": [], in .vscode\settings.json is the folder path of the tested file, for example, my test file is in Test_cc under the a folder.

>      "python.testing.pytestArgs": [
>             "a/Test_cc"
>         ],

If this is not what you want, please let me know and describe the details of your needs.

Reference: Debug tests.

Update:

Usually, when we debug the test in VSCode, without setting a breakpoint for it, it will only display the test result. (success or failure). It will only display relevant test information in the console OUTPUT.

When I use the extension 'Python Test Explorer for Visual Studio code', it will display the debugging test information on the console, prompting the issue.

I encountered the same issue and your post almost solves the problem. When I tried implementing your solution I encountered the following issue:

ImportError while loading conftest '/app/tests/conftest.py'.
     tests/conftest.py:36: in <module>
ptvsd.enable_attach("secret_text", address=("0.0.0.0", 5678))
E   TypeError: enable_attach() got multiple values for argument 'address'

Removing the "secret_text" value allowed me to hit the wait_for_attach() point and successfully attach the debugger to the code. I was able to hit breakpoints in my tests. Thank you!

.vscode/launch.json

{
  "name": "Python: Attach",
  "type": "python",
  "request": "attach",
  "localRoot": "${workspaceFolder}/path/to/code",
  "remoteRoot": "/app",
  "port": 5678,
  "host": "localhost"
}

docker-compose.yml

ports:
 - "5678:5678"

conftest.py

import ptvsd
ptvsd.enable_attach(address=("0.0.0.0", 5678))
ptvsd.wait_for_attach()

Note: The ptvsd lines are placed after all the imports.

CLI command to execute tests:

import subprocess
import click

@click.command()
def cli():
    return subprocess.call("pytest test", shell=True)

Sequence to debug tests:

1. docker-compose up (get container running)
2. docker-compose exec MODULE CONTAINER_NAME FUNCTION_THAT_EXECUTES_TEST
3. Attach debugger in VSCode

Tests will execute and hit whatever breakpoint you have setup.

pytest-env

Install

Per https://stackoverflow.com/a/39162893/13697228:

conda install -c conda-forge pytest-env

Or:

pip install pytest-env

pytest.ini

Create pytest.ini file in project directory:

[pytest]
env = 
    ENV_VAR=RandomStuff

Python

In your code, load environment variables as you normally would:

import os
env_var = os.environ["ENV_VAR"]

pytest / VS Code

Either run:

pytest

(Notice how it says configfile: pytest.ini)

C:\Users\sterg\Documents\GitHub\sparks-baird\mp-time-split> pytest
==================================== test session starts ===================================== platform win32 -- Python 3.9.12, pytest-7.1.1, pluggy-1.0.0 rootdir:
C:\Users\sterg\Documents\GitHub\sparks-baird\mp-time-split,
configfile: pytest.ini plugins: anyio-3.6.1, cov-3.0.0, env-0.6.2
collecting ...

Or:

This only seems to work with breakpoints that have manually been set, I'm guessing some other change is needed to pause on errors.

Python for VS Code Extension

Apparently the Python for VS Code extension recognizes a .env file automatically. E.g. .env file:

ENV_VAR=RandomStuff

Haven't verified, but I'd assume this has the same behavior as using pytest-env with a pytest.ini file.

When all else fails

When I don't feel like dealing with the strange hackery necessary to get VS Code, Anaconda environments, and pytest playing nicely together (and/or forget how I fixed it before), I call my tests manually and run it like a normal script (see below). This may not work with more advanced pytest trickery using fixtures for example. At the end of your Python script, you can add something like:

if __name__ == "__main__":
    my_first_test()
    my_second_test()

and run it in debug mode (F5) as normal.