Test discovery hangs indefinitely with WSL2 and uv venv

[bewing]

Type: Bug

Behaviour

Attempting to discover tests hangs indefinitely

Steps to reproduce:

1. Clone several git repositories into a new, empty folder
2. Manually create venv in folder via uv venv --python 3.11.11
3. Launch vscode in folder, select python venv interpreter
4. Configure pytest tests
5. Click on test icon in left bar

Diagnostic data

Output for Python in the Output panel (View→Output, change the drop-down the upper-right of the Output panel to Python)

2025-03-26 14:39:02.945 [info] Experiment 'pythonRecommendTensorboardExt' is active
2025-03-26 14:39:02.946 [info] Experiment 'pythonSurveyNotificationcf' is active
2025-03-26 14:39:02.946 [info] Experiment 'pythonTerminalEnvVarActivation' is active
2025-03-26 14:39:02.946 [info] Experiment 'pythonTestAdapter' is active
2025-03-26 14:39:02.946 [info] Native locator: Refresh started
2025-03-26 14:39:02.960 [info] Poetry environment manager found at: /home/bewing/.local/share/pypoetry/venv/bin/poetry
2025-03-26 14:39:03.135 [info] Native locator: Refresh finished in 644 ms
2025-03-26 14:39:03.139 [info] Python interpreter path: ./.venv/bin/python
2025-03-26 14:39:04.669 [info] > pyenv which python
2025-03-26 14:39:04.669 [info] cwd: .
2025-03-26 14:39:06.551 [info] > . ./.venv/bin/activate && echo 'e8b39361-0157-4923-80e1-22d70d46dee6' && python ~/.vscode-server-insiders/extensions/ms-python.python-2025.3.2025032601-linux-x64/python_files/printEnvVariables.py
2025-03-26 14:39:06.551 [info] shell: bash
2025-03-26 14:39:06.722 [info] > /bin/python ~/.vscode-server-insiders/extensions/ms-python.python-2025.3.2025032601-linux-x64/python_files/printEnvVariables.py
2025-03-26 14:39:06.722 [info] shell: bash
2025-03-26 14:39:07.083 [info] Setting environment variable VIRTUAL_ENV in collection to /home/bewing/Projects/naac/.venv {"applyAtShellIntegration":true,"applyAtProcessCreation":true}
2025-03-26 14:39:07.083 [info] Setting environment variable VIRTUAL_ENV_PROMPT in collection to (naac)  {"applyAtShellIntegration":true,"applyAtProcessCreation":true}
2025-03-26 14:39:07.083 [info] Prepending environment variable PS1 in collection with (naac)  {"applyAtShellIntegration":true,"applyAtProcessCreation":false}
2025-03-26 14:39:07.083 [info] Prepending environment variable PATH in collection with /home/bewing/.vscode-server-insiders/extensions/ms-python.python-2025.3.2025032601-linux-x64/python_files/deactivate/bash:/home/bewing/Projects/naac/.venv/bin: {"applyAtShellIntegration":true,"applyAtProcessCreation":true}
2025-03-26 14:39:07.084 [info] Send text to terminal: /bin/python /home/bewing/.vscode-server-insiders/extensions/ms-python.python-2025.3.2025032601-linux-x64/python_files/printEnvVariablesToFile.py /home/bewing/.vscode-server-insiders/extensions/ms-python.python-2025.3.2025032601-linux-x64/python_files/deactivate/bash/envVars.txt
2025-03-26 14:39:07.987 [info] Starting Pylance language server.
2025-03-26 14:39:18.998 [debug] Testing: Refreshing all test data
2025-03-26 14:39:18.999 [info] Discover tests for workspace name: naac - uri: /home/bewing/Projects/naac
2025-03-26 14:39:19.004 [debug] Starting Test Discovery named pipe

Extension version: 2025.3.2025032601
VS Code version: Code - Insiders 1.99.0-insider (87a35e1, 2025-03-26T05:03:45.940Z)
OS version: Windows_NT x64 10.0.22000
Modes:
Remote OS version: Linux x64 5.15.167.4-microsoft-standard-WSL2

• Python version (& distribution if applicable, e.g. Anaconda): 3.11.11
• Type of virtual environment used (e.g. conda, venv, virtualenv, etc.): Venv
• Value of the python.languageServer setting: Default

User Settings

languageServer: "Pylance"

testing
• pytestArgs: "<placeholder>"
• pytestEnabled: true

terminal
• launchArgs: "<placeholder>"

Installed Extensions

Extension Name	Extension Id	Version
ansible	red	25.3.1
black-formatter	ms-	2025.2.0
debugpy	ms-	2025.5.2025031101
django-intellisense	sha	0.0.2
django-test-runner	Pac	4.0.2
doxdocgen	csc	1.4.0
even-better-toml	tam	0.21.2
file-downloader	min	1.0.13
gitblame	wad	11.1.2
gitlab-workflow	Git	5.13.0
gitlens	eam	16.3.3
go	gol	0.46.1
isort	ms-	2023.10.1
js-debug	ms-	1.97.1
jsoncrack-vscode	Ayk	3.0.0
jupyter	ms-	2025.2.0
jupyter-renderers	ms-	1.1.0
prettier-vscode	esb	11.0.0
python	ms-	2025.3.2025032601
Rcf-VS-Code-Plugin	ari	4.32.2
reflow-markdown	mar	3.1.0
shellcheck	tim	0.37.7
svn-scm	joh	2.17.0
vscode-docker	ms-	1.29.4
vscode-js-profile-table	ms-	1.0.10
vscode-jupyter-cell-tags	ms-	0.1.9
vscode-jupyter-slideshow	ms-	0.1.6
vscode-kubernetes-tools	ms-	1.3.20
vscode-markdownlint	Dav	0.59.0
vscode-pull-request-github	Git	0.106.0
vscode-pylance	ms-	2025.3.103
vscode-xml	red	0.28.2025031108
vscode-yaml	red	1.17.0
win-ca	uko	3.5.1
xml	Dot	2.5.1

System Info

Item	Value
CPUs	Intel(R) Xeon(R) Silver 4114 CPU @ 2.20GHz (40 x 2195)
GPU Status	2d_canvas: enabled canvas_oop_rasterization: enabled_on direct_rendering_display_compositor: disabled_off_ok gpu_compositing: enabled multiple_raster_threads: enabled_on opengl: enabled_on rasterization: enabled raw_draw: disabled_off_ok skia_graphite: disabled_off video_decode: enabled video_encode: enabled vulkan: disabled_off webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off
Load (avg)	undefined
Memory (System)	94.66GB (63.75GB free)
Process Argv	--crash-reporter-id 14b65026-3b4e-4592-bbc1-17245674ffe8
Screen Reader	no
VM	0%

Item	Value
Remote	WSL: Ubuntu
OS	Linux x64 5.15.167.4-microsoft-standard-WSL2
CPUs	Intel(R) Xeon(R) Silver 4114 CPU @ 2.20GHz (40 x 0)
Memory (System)	46.38GB (41.01GB free)
VM	0%

A/B Experiments

vsliv368:30146709
vspor879:30202332
vspor708:30202333
vspor363:30204092
pythonvspyt551cf:31249598
vscod805cf:30301675
py29gd2263:31024238
c4g48928:30535728
vscrp:30624060
a9j8j154:30646983
962ge761:30841072
dsvsc014:30777825
dsvsc015:30821418
h48ei257:31000450
pythontbext0:30879054
cppperfnew:30980852
dwnewjupyter:31046869
nativerepl1:31134653
pythonrstrctxt:31093868
nativeloc1:31118317
e80f6927:31120813
iacca1:31150324
dwcopilot:31158714
c3hdf307:31184662
6074i472:31201624
dwoutputs:31242946
customenabled:31248079
9064b325:31222308
copilot_t_ci:31222730
850i5325:31264362
g012b348:31231168
jda6j935:31233686
copilothoveron:31262361
pythoneinst12:31251391
bgtreat:31252123
fh1c7952:31247580
31787653:31262186
3e8i5726:31266632
pythonpulldiag:31258010
6gi0g917:31259950
editor719:31268331
996jf627:31264550
pythonrdcb7:31268811

[bewing]

Adding
"python.experiments.optOutFrom": ["pythonTestAdapter"]

to settings.json does not alter behavior

[bewing]

I have also tried:

closing all vscode insider instances
uninstalling vscode insider
removing ~/.vscode-insider/extensions
re-installing vscode insider
re-opening the project in WSL vscode insider

still hangs.

[bewing]

Nuking ~/.vscode-server-insiders inside WSL2 appears to have resolved.