What is genvm-lint and How to Use It for GenLayer Smart Contracts

genvm-lint is a static analysis tool that validates GenLayer intelligent contracts for deployment-blocking errors in approximately 250 milliseconds per file.

genvm-lint ships as the genvm-linter package in the genlayerlabs/genlayer-project-boilerplate repository. It performs pre-deployment validation to catch forbidden imports, incorrect storage types, and missing decorators before contracts reach the GenLayer Studio environment.

What is genvm-lint?

genvm-lint is the command-line interface bundled inside the genvm-linter Python package. It statically analyzes intelligent contracts written for the GenLayer Virtual Machine (GenVM) to enforce deterministic execution rules. According to the source code in genlayer-project-boilerplate, the tool completes validation in roughly 250 ms per contract, making it suitable for rapid iteration during development.

The linter validates compliance with GenLayer's unique execution model, where contracts must avoid non-deterministic operations unless properly isolated. This catches errors that would otherwise block deployment to the GenLayer Studio environment.

Installation and Setup

The genvm-linter package is listed as a dependency in the project's requirements.txt at line 3. Install it alongside other development dependencies:

pip install -r requirements.txt

This installs the genvm-lint CLI globally within your Python environment, making it available for local validation and CI/CD pipelines.

Linting Rules and Validation Checks

The validation rules enforced by genvm-lint are documented in the repository's README.md (lines 62-67). The tool performs four critical categories of checks:

• Forbidden imports: Blocks imports of os, sys, subprocess, and other modules that could introduce non-deterministic behavior or security vulnerabilities.
• Correct storage types: Enforces use of GenLayer-specific containers like TreeMap, DynArray, and u256 instead of native Python lists, dictionaries, or integers.
• Required decorators: Validates that contract methods use @gl.public.view or @gl.public.write decorators and include proper return-type annotations.
• Equivalence-principle compliance: Ensures non-deterministic operations are wrapped in equivalence-principle blocks to guarantee consistent execution across validator nodes.

How to Run genvm-lint Locally

Validate individual contracts or entire directories using the genvm-lint check command. The basic syntax follows the pattern documented in README.md (lines 54-60):

Check a single contract:

genvm-lint check contracts/football_bets.py

Check all contracts in a directory:

genvm-lint check contracts/*.py

The tool outputs specific line-by-line diagnostics for any violations, allowing developers to fix storage type mismatches or missing decorators before running tests.

CI/CD Integration with GitHub Actions

The repository includes an automated workflow in .github/workflows/ci.yml (lines 14-20) that executes genvm-lint on every push and pull request. The configuration installs dependencies from requirements.txt then runs the linter against the sample contract:

jobs:
  lint-contracts:
    name: Lint Contracts
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-python@v5
        with:
          python-version: "3.12"
      - run: pip install -r requirements.txt
      - run: genvm-lint check contracts/football_bets.py

This ensures that no contract violating GenVM rules merges into the main branch.

Typical Development Workflow

The boilerplate project structures development around genvm-lint as a gate between editing and testing:

1. Edit contract code in contracts/my_contract.py.
2. Validate with genvm-lint using genvm-lint check contracts/my_contract.py and fix reported issues.
3. Run direct-mode tests with pytest tests/direct/ -v for fast, in-memory validation (milliseconds per test).
4. Execute integration tests using gltest tests/integration/ -v -s against GenLayer Studio once linting passes.

Because genvm-lint validates contracts statically, it catches deployment-blocking issues early, allowing developers to rely on the fast direct-mode tests before committing to slower full-stack integration testing.

Summary

• genvm-lint is a ~250 ms static analysis tool bundled in the genvm-linter package.
• It enforces four rule categories: forbidden imports, storage types, decorators, and equivalence-principle compliance.
• Install via requirements.txt (line 3) and run with genvm-lint check <file>.
• The tool integrates automatically into CI via .github/workflows/ci.yml.
• It serves as the first validation gate in the development workflow before direct-mode and integration testing.

Frequently Asked Questions

What does genvm-lint check for?

genvm-lint validates four specific categories of GenLayer contract requirements: forbidden system imports (like os and sys), correct usage of storage types (TreeMap, DynArray, u256), mandatory method decorators (@gl.public.view, @gl.public.write), and equivalence-principle compliance for non-deterministic operations.

How fast is genvm-lint?

The tool executes in approximately 250 milliseconds per contract, making it significantly faster than full integration tests. This speed allows developers to run the linter continuously during development without interrupting workflow.

Can I run genvm-lint on multiple contracts at once?

Yes. While you can validate single files with genvm-lint check contracts/football_bets.py, the CLI accepts glob patterns like genvm-lint check contracts/*.py to validate entire directories in a single command.

Is genvm-lint required before deploying to GenLayer Studio?

While the linter itself is a development tool, the rules it enforces are mandatory for successful deployment. Contracts that fail genvm-lint validation contain errors that GenLayer Studio will reject, making the linter an essential pre-deployment step in the development workflow.

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