PythonTA Checker
See exactly what PythonTA will flag, as squiggles in VS Code. One click installs everything, no pip install.
Built for University of Toronto courses that grade with PythonTA. Not affiliated with the University of Toronto or the PythonTA maintainers.
Why
- No install step. PythonTA and everything it needs ship inside the extension. You only need Python 3.10 or newer, which the course already requires.
- Matches the grader. Course starter files end with
python_ta.check_all(config={...}). The extension reads that block and applies the same config, so you don't get false positives like "forbidden import random" that the grader would never report.
- Only PythonTA. By default, Pylance and basedpyright problems are hidden so the Problems panel shows one source of truth and nothing overlaps. Autocomplete keeps working. One command turns it back.
- Never runs your file. Files are parsed, not executed.
Install
- Install Python 3.10+ if you haven't already.
- Install PythonTA Checker from the VS Code Marketplace. The Python extension comes with it.
- Problems appear when you open or save a file. With autosave on, they refresh about a second after you stop typing. Click PyTA on the bottom status bar to re-check.
The extension only works in a trusted workspace. VS Code asks you to trust a folder the first time you open it.
Reading the squiggles
- Red is a PythonTA error. Yellow is everything else: warnings, style and convention messages. The grader reports both.
- Hover a squiggle and click the code (for example
E9999) to open the PythonTA page for that message. It explains what is wrong and how to fix it.
Commands
| Command |
What it does |
PythonTA: Check Current File (Ctrl+Alt+T, Cmd+Alt+T on macOS, Ctrl+Alt+Shift+T on Linux) |
Save and check the current file now. |
| PythonTA: Toggle Only-PythonTA Problems |
Show or hide Pylance and basedpyright problems. |
| PythonTA: Restart Server |
Restart the checker, for example after installing a different Python. |
| PythonTA: Show Output Log |
Open the PythonTA log. |
Settings
| Setting |
Default |
Meaning |
pythonta.hideOtherPythonDiagnostics |
true |
Hide Pylance and basedpyright problems. Use the toggle command rather than editing this by hand. |
pythonta.runOnSave |
true |
Check a file each time it is saved. |
pythonta.runOnOpen |
true |
Check a file when it is opened. |
pythonta.configPath |
"" |
PythonTA config file to use when the file has no check_all(config=...) of its own. Relative to the workspace folder. |
pythonta.importStrategy |
useBundled |
useBundled uses the PythonTA inside the extension. fromEnvironment prefers the PythonTA installed in your selected interpreter. |
pythonta.interpreter |
"" |
Path to a Python executable, if you want to override the one the Python extension picked. |
If you uninstall the extension while Only PythonTA is on, Pylance problems stay hidden, because VS Code gives extensions no chance to clean up. Run the toggle command first, or delete the two analysis.ignore lines from your settings.json.
Other editors
I don't use VS Code anymore, I use Zed, so the next step is a Zed extension. Other editors after that. The checker is a standalone language server (python -m pyta_lsp over stdio), so any editor that speaks LSP can use it already. If you want a specific editor, open a GitHub issue.
Troubleshooting
If nothing appears, open View > Output and pick PythonTA from the dropdown. The log says which Python was found and what the checker did.
If the course config has a problem PythonTA complains about, you get an information message on line 1 naming the config file, so a broken config never fails silently.
Still stuck? Open an issue with the log and the file.
Contributing
python -m venv .venv
.venv/Scripts/python -m pip install -e "server[dev]" # POSIX: .venv/bin/python
.venv/Scripts/python scripts/bundle.py build # builds bundled/libs, needed to run the extension
npm ci && npm test # type-check, lint, unit tests
.venv/Scripts/python -m pytest server/tests -q # server tests
License
MIT. See LICENSE.
The extension bundles unmodified third-party Python packages; see THIRD_PARTY_NOTICES.md for the list and their licenses. PythonTA's package metadata declares MIT while its repository LICENSE file is GPL-3.0; this project redistributes the published wheel unchanged. See https://github.com/pyta-uoft/pyta.
