Incorrect django test coverage report with parallel tests

[sainak]

Type: Bug

Behaviour

Running tests in parallel with coverage gives incorrect results

Steps to reproduce:

1. Create django unittest suites

2. Use the follwing test args:

"python.testing.unittestArgs": [
    "--noinput",
    "--shuffle",
    "--parallel",
    "--keepdb"
  ],

3. Tun the tests with coverage

Expected behaviour

The extension should combine the test results from parallel runs while reporting the coverage

ref: https://docs.djangoproject.com/en/5.2/internals/contributing/writing-code/unit-tests/#code-coverage

Diagnostic data

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

2025-11-19 14:30:09.274 [info] MANAGE_PY_PATH is set, running Django discovery with path to manage.py as: $./manage.py

2025-11-19 14:30:09.274 [info] Running Django tests with command: ['/Users/user/.local/share/virtualenvs/dj-app-tnTrOaDS/bin/python', './manage.py', 'test', '--testrunner=django_test_runner.CustomDiscoveryTestRunner', '--noinput', '--shuffle', '--parallel', '--keepdb']

2025-11-19 14:30:11.327 [error] 

2025-11-19 14:30:11.327 [info] Using shuffle seed: 7640050632 (generated)
Found 1152 test(s).


2025-11-19 14:30:14.071 [info] Running UNITTEST execution for the following test ids: ....


2025-11-19 14:32:02.180 [info] Attempting to use temp directory for test ids file, file name: test-ids-11f98e997c358961993b.txt
2025-11-19 14:32:02.181 [info] All environment variables set for unittest execution, PYTHONPATH: "/Users/user/Projects/dj-app"
2025-11-19 14:32:02.182 [info] Running unittests for workspace /Users/user/Projects/dj-app with arguments: /Users/user/.vscode/extensions/ms-python.python-2025.18.0-darwin-arm64/python_files/unittestadapter/execution.py,--udiscovery,--noinput,--shuffle,--parallel,--keepdb

2025-11-19 14:32:02.182 [info] > ~/.local/share/virtualenvs/dj-app-tnTrOaDS/bin/python ~/.vscode/extensions/ms-python.python-2025.18.0-darwin-arm64/python_files/unittestadapter/execution.py --udiscovery --noinput --shuffle --parallel --keepdb
2025-11-19 14:32:02.182 [info] cwd: .
2025-11-19 14:32:31.350 [info] Test Result named pipe /var/folders/0n/4qvkqnzs3sl7w6m5vb1vxn9m0000gn/T/python-test-results-be3ef89e529d3fca4b1f  cancelled

Extension version: 2025.18.0
VS Code version: Code 1.106.1 (cb1933bbc38d329b3595673a600fab5c7368f0a7, 2025-11-16T10:20:23.745Z)
OS version: Darwin arm64 25.1.0
Modes:

• Python version (& distribution if applicable, e.g. Anaconda): 3.13.9
• Type of virtual environment used (e.g. conda, venv, virtualenv, etc.): PipEnv
• Value of the python.languageServer setting: Pylance

User Settings

languageServer: "Pylance"

testing
• unittestArgs: "<placeholder>"
• unittestEnabled: true

terminal
• activateEnvironment: false

Installed Extensions

Extension Name	Extension Id	Version
astro-vscode	ast	2.15.4
azure-repos	ms-	0.40.0
biome	bio	3.3.0
black-formatter	ms-	2025.2.0
Bookmarks	ale	13.5.0
boto3-ide	Bot	0.6.0
code-spell-checker	str	4.3.2
codespaces	Git	1.18.0
copilot	Git	1.388.0
copilot-chat	Git	0.33.1
cpptools	ms-	1.28.3
debugpy	ms-	2025.16.0
docker	doc	0.18.0
even-better-toml	tam	0.21.2
gc-excelviewer	Gra	4.2.64
git-graph	mhu	1.30.0
github-vscode-theme	Git	6.3.5
gitlens	eam	17.7.1
go	gol	0.50.0
isort	ms-	2025.0.0
js-debug	ms-	1.105.0
js-debug-companion	ms-	1.1.3
jupyter	ms-	2025.9.1
jupyter-keymap	ms-	1.1.2
jupyter-renderers	ms-	1.3.0
latex-workshop	Jam	10.11.3
live-server	ms-	0.4.16
LiveServer	rit	5.7.9
material-icon-theme	PKi	5.28.0
postgrestools	Sup	1.3.2
prettier-vscode	esb	11.0.0
pretty-ts-errors	Yoa	0.6.1
prisma	Pri	6.19.0
python	ms-	2025.18.0
python-path	mge	0.0.14
remote-containers	ms-	0.431.1
remote-explorer	ms-	0.5.0
remote-repositories	ms-	0.42.0
remote-ssh	ms-	0.120.0
remote-ssh-edit	ms-	0.87.0
remotehub	Git	0.64.0
rescript-vscode	che	1.66.0
ruby-lsp	Sho	0.9.32
ruff	cha	2025.28.0
rust-analyzer	rus	0.3.2683
sorbet-vscode-extension	sor	0.3.46
svelte-vscode	sve	109.12.0
tauri-vscode	tau	0.2.9
todo-tree	Gru	0.0.226
vscode-containers	ms-	2.3.0
vscode-coverage-gutters	rya	2.14.0
vscode-docker	ms-	2.0.0
vscode-eslint	dba	3.0.16
vscode-firefox-debug	fir	2.15.0
vscode-github-actions	git	0.28.0
vscode-js-profile-table	ms-	1.0.10
vscode-jupyter-cell-tags	ms-	0.1.9
vscode-jupyter-slideshow	ms-	0.1.6
vscode-pull-request-github	Git	0.122.0
vscode-pylance	ms-	2025.9.1
vscode-python-envs	ms-	1.12.0
vscode-scss	mrm	0.10.0
vscode-styled-jsx-syntax	Div	1.3.1
vscode-tailwindcss	bra	0.14.29
vscode-theme-onedark	aka	2.3.0
vscode-thunder-client	ran	2.38.5
vsliveshare	ms-	1.0.5959

System Info

Item	Value
CPUs	Apple M2 (8 x 2400)
GPU Status	2d_canvas: enabled 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: enabled_on trees_in_viz: disabled_off video_decode: enabled video_encode: enabled webgl: enabled webgl2: enabled webgpu: enabled webnn: disabled_off
Load (avg)	18, 7, 5
Memory (System)	16.00GB (0.30GB free)
Process Argv
Screen Reader	no
VM	0%

[sainak]

Related:

• Django test coverage #25664