title: Debug Test in vscode fails inside container
body: <h2>Configuration:</h2>
  <p>I am using the following version of VSCode:</p>
  <pre><code>Version: 1.46.1
  Commit: cd9ea6488829f560dc949a8b2fb789f3cdc05f5d
  Date: 2020-06-17T21:13:08.304Z
  Electron: 7.3.1
  Chrome: 78.0.3904.130
  Node.js: 12.8.1
  V8: 7.8.279.23-electron.0
  OS: Linux x64 5.3.0-59-generic snap
  </code></pre>
  <p>With the Python Extension <code>ms-python.python</code> version <code>v2020.6.8</code>. The only PIPs installed are:</p>
  <pre><code>Package           Version
  ----------------- -------
  astroid           2.4.2
  attrs             19.3.0
  autopep8          1.5.3
  isort             4.3.21
  lazy-object-proxy 1.4.3
  mccabe            0.6.1
  more-itertools    8.4.0
  packaging         20.4
  pip               20.1.1
  pluggy            0.13.1
  py                1.8.2
  pycodestyle       2.6.0
  pylint            2.5.3
  pyparsing         2.4.7
  pytest            5.4.3
  setuptools        47.1.1
  six               1.15.0
  toml              0.10.1
  wcwidth           0.2.4
  wheel             0.34.2
  wrapt             1.12.1
  </code></pre>
  <h2>Problem:</h2>
  <p>I am trying to debug my python tests in vscode and i get the following error in the debug console:</p>
  <pre><code>============================= test session starts ==============================
  platform linux -- Python 3.8.3, pytest-5.4.3, py-1.8.2, pluggy-0.13.1
  rootdir: /workspaces/test_python_debugging
  collected 0 items / 1 error
  
  ==================================== ERRORS ====================================
  _________________ ERROR collecting tst/dummy/test_unit_math.py _________________
  ImportError while importing test module '/workspaces/test_python_debugging/tst/dummy/test_unit_math.py'.
  Hint: make sure your test modules/packages have valid Python names.
  Traceback:
  tst/dummy/test_unit_math.py:5: in &lt;module&gt;
      from dummy.math import add
  E   ModuleNotFoundError: No module named 'dummy'
  --------------- generated xml file: /tmp/tmp-188wLObs4r6II9x.xml ---------------
  =========================== short test summary info ============================
  ERROR tst/dummy/test_unit_math.py
  =============================== 1 error in 0.19s ===============================
  ERROR: not found: /workspaces/test_python_debugging/tst/dummy/test_unit_math.py::test_addition
  (no name '/workspaces/test_python_debugging/tst/dummy/test_unit_math.py::test_addition' in any of [&lt;Module tst/dummy/test_unit_math.py&gt;])
  </code></pre>
  <p>The tests themselves run fine in the terminal. In other terms there is no issue with not being able to find the &quot;missing&quot; module. Example:</p>
  <pre><code>0f617e2a72ee [/workspaces/test_python_debugging]$ python -m pytest tst/**/te
  st*.py -k test_addition
  =========================== test session starts ============================
  platform linux -- Python 3.8.3, pytest-5.4.3, py-1.8.2, pluggy-0.13.1
  rootdir: /workspaces/test_python_debugging
  collected 1 item                                                           
  
  tst/dummy/test_unit_math.py .                                        [100%]
  
  ============================ 1 passed in 0.01s =============================
  0f617e2a72ee [/workspaces/test_python_debugging]$ 
  </code></pre>
  <p>The way I am launching the debugger is by clicking on the <code>Debug Test</code> link for the given test. Example:</p>
  <p><a href="https://i.stack.imgur.com/0Q9TM.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/0Q9TM.png" alt="Launching debugger on test" /></a></p>
  <p>Below is the <code>.devcontainer.json</code> configuration being used:</p>
  <pre><code>{
    &quot;image&quot;: &quot;test_python_debugging&quot;,
    &quot;extensions&quot;: [
      &quot;ms-python.python&quot;
    ],
    &quot;mounts&quot;: [
      &quot;source=${localWorkspaceFolder},target=/app,type=bind,consistency=cached&quot;
    ],
    &quot;settings&quot;: {
      &quot;terminal.integrated.shell.linux&quot;: &quot;/bin/ash&quot;,
      &quot;terminal.integrated.shellArgs.linux&quot;: [
        &quot;-l&quot;
      ],
      &quot;python.testing.pytestArgs&quot;: [
        &quot;tst&quot;,
        &quot;-k test_unit&quot;
      ],
      &quot;python.testing.unittestEnabled&quot;: false,
      &quot;python.testing.nosetestsEnabled&quot;: false,
      &quot;python.testing.pytestEnabled&quot;: true,
      &quot;python.linting.enabled&quot;: true,
      &quot;python.linting.pylintEnabled&quot;: true,
      &quot;python.pythonPath&quot;: &quot;/usr/local/bin/python&quot;
    },
    &quot;containerUser&quot;: &quot;app&quot;,
    &quot;containerEnv&quot;: {
      &quot;PYTHONPATH&quot;: &quot;/app/src&quot;
    }
  }
  </code></pre>
  <p>Would someone know what I am missing in terms of configurations?</p>