coding-platform

About this project

coding-platform is an immersive, assessment-first coding environment built for learning, interviews, and secure timed evaluations. It blends a friendly editor experience with strict integrity controls so instructors and contest hosts can focus on evaluating skill — not chasing down accidental shortcuts.

Key ideas:

• Immersive assessments: during exam or contest mode the UI is intentionally locked down — copying and pasting is restricted, right-click/context menus and developer tools are disabled, and focus is maintained to discourage tab-switching and external lookups.
• Fairness by design: the platform records audit logs and enforces resource limits and per-job isolation so every submission runs in the same, reproducible environment.
• Fast feedback: testcases run inside lightweight language sandboxes and return rich structured results . so learners see useful, actionable feedback immediately.
• Multi-language and function-first: supports Python, Java, Node.js, C and C++ and includes helpers to accept function-only submissions and wrap them safely for execution.

This project aims to be practical for instructors and delightful for learners — combining robust sandboxing with a clean, distraction-minimizing UX.

Quick start (local development)

Prerequisites

• Git
• Node.js and npm (tested with Node.js v24.12.0, npm 11.6.2)
• Docker, installed and running. The backend runs submitted code inside Docker containers, so code execution fails without it.
  • On Windows, install Docker Desktop with the WSL 2 backend (wsl --install in an admin PowerShell, then restart).
  • Check it works with docker info.

Windows users: run git config --global core.autocrlf input before cloning. Otherwise Git converts the shell scripts in judge/ to CRLF line endings, which breaks them inside the Linux containers (see Troubleshooting).

1. Clone the repository

git clone https://github.com/osl-vvce/coding-platform.git
cd coding-platform

2. Build the judge images

Run these from the project root. Each language needs its own image; build only the ones you need.

docker build -t coding-judge-python judge/images/python
docker build -t coding-judge-java   judge/images/java
docker build -t coding-judge-node   judge/images/node
docker build -t coding-judge-c      judge/images/c
docker build -t coding-judge-cpp    judge/images/cpp

3. Start the backend

cd server
npm install
npm start

The server listens on port 3001 (override with the PORT environment variable). Leave this terminal running.

4. Start the frontend

In a second terminal, from the project root:

npm install
npm start

Open http://localhost:3000.

5. Verify it works

Choose Python, replace the code with the following, and click Run Code:

def solve(data):
    return "hii"

You should see stdout: hii and exit code: 0. Test cases may show "Failed" for placeholder code; that is expected.

Environment variables

The frontend sends requests to http://localhost:3001 by default. To point it at a different backend, copy .env.example to .env.local in the project root:

REACT_APP_API_BASE_URL=http://localhost:3001

Restart npm start after changing it.

Troubleshooting

Error	Cause	Fix
"Internal Server Error" in the editor; backend logs spawn docker ENOENT	Docker is not installed, not running, or not on your PATH	Install and start Docker Desktop, open a new terminal, and confirm docker info works
Unable to find image 'coding-judge-<lang>:latest' locally	The judge image for the selected language has not been built	Run the matching docker build -t coding-judge-<lang> judge/images/<lang> command
/bin/sh: 1: /usr/local/bin/compile: not found (Windows)	Git converted judge/ scripts to CRLF line endings	Run git config core.autocrlf input, delete and re-checkout the judge/ folder (git checkout -- judge), then rebuild with docker build --no-cache -t coding-judge-<lang> judge/images/<lang>
NameError: name 'solve' is not defined	The platform calls a function named solve in your code	Define def solve(data): ...

npm install prints many deprecation warnings and npm audit findings. These come from old pinned dependencies and are safe to ignore for local development.

Running the backend tests

The /execute API is covered by Jest + Supertest tests in server/tests/execute.test.js. Docker is mocked, so you do not need Docker or the judge images to run them.

cd server
npm install
npm test

The suite covers passing and failing submissions, compile errors, runtime errors, an empty body, missing or malformed fields, unsupported languages and Docker being unavailable.

Developer notes

• Frontend now calls the Docker-backed /execute endpoint and shows compileError, stderr, and non-zero exit statuses prominently.
• REACT_APP_API_BASE_URL is used for configuring the API base URL in different environments.

Tech stack

• Backend: Node.js (Express)
• Frontend: React (Create React App) and CodeMirror for the editor
• Sandboxing: Docker judge images (GCC for C/C++, Temurin JDK for Java, Python 3, Node.js)