How to Run Tests for denoland/celld: Complete Guide with Cargo and Docker

Run tests for denoland/celld using cargo test --all --locked for local development or docker build for an isolated, CI-matching environment.

The denoland/celld repository is a Rust-based distributed systems project that uses Cargo's native test framework. This guide covers both local and containerized testing workflows, referencing the actual source structure and CI configuration used by the Deno team.

---

Prerequisites: Rust Toolchain

Before running any tests, you need a working Rust installation. The repository tracks dependency versions precisely through Cargo.lock, so any recent stable toolchain will suffice.

Install Rust via rustup:

curl https://sh.rustup.rs -sSf | sh
source $HOME/.cargo/env

Verify installation:

cargo --version

---

Local Testing with Cargo

Run the Complete Test Suite

Navigate to your local copy of the repository and execute:

git clone https://github.com/denoland/celld.git
cd celld
cargo test --all --locked

The --all flag runs tests across the entire workspace. The --locked flag forces Cargo to use exact versions from Cargo.lock, ensuring reproducible results that match CI behavior. This flag is critical for debugging issues that appear in automated builds.

Run Tests for a Single Crate

For faster iteration on specific components, target individual crates with the -p flag:

cargo test -p ltx

This command only executes tests for the ltx crate, skipping unrelated code paths. Other available crates depend on your checkout; inspect Cargo.toml at the workspace root for the full member list.

---

Containerized Testing with Docker

The repository includes a Dockerfile that executes tests during the image build process. This method guarantees an environment identical to production CI.

Build and Test in One Command

docker build -t celld-test .

The Dockerfile contains the following test invocation at line 33:

cargo test --profile "${CELLD_PROFILE}" --locked && \

If any test fails, the Docker build fails immediately—mirroring how CI evaluates pull requests.

When to Use Docker Testing

• Reproducing CI failures when local results differ
• Isolated environments without Rust installed
• Verifying environment-specific bugs related to system libraries

---

Understanding the Test Architecture

The denoland/celld testing philosophy is documented in docs/testing.md. The test suite spans four verification layers:

1. Conformance tests – Validate protocol compatibility
2. Specification tests – Verify behavior against formal specs
3. Simulation tests – Model distributed system scenarios
4. Live-fleet tests – Exercise real deployment conditions

Most developers only need to run the first three layers via cargo test. Live-fleet tests require Cloudflare Workers infrastructure via wrangler and are gated behind feature flags. These integration tests skip automatically unless specific environment variables are present.

---

Key Files for Test Configuration

File	Purpose
Cargo.toml	Workspace manifest declaring member crates and dev-dependencies
Cargo.lock	Pinned dependency versions; required for --locked reproducibility
Dockerfile	CI-style container definition with embedded test commands
docs/testing.md	Architecture documentation for the four testing layers
.github/workflows/release.yml	GitHub Actions workflows invoking the same test commands

---

Troubleshooting Common Issues

Dependency Version Mismatches

If tests pass locally but fail in CI, verify you're using --locked:

cargo test --all --locked

Without this flag, Cargo may resolve newer dependencies than those pinned in Cargo.lock.

Cloudflare Workers Tests Skipped

This is expected behavior. Integration tests requiring wrangler only execute when CF_ACCOUNT_ID and related variables are configured. For standard development, skipped tests indicate correct configuration.

Build Failures in Docker

Ensure your Docker daemon can access the repository network for base image pulls. The Dockerfile uses multi-stage builds with Rust compilation, requiring substantial memory—allocate at least 4GB to the Docker VM.

---

Summary

• cargo test --all --locked runs the full local test suite with reproducible dependencies
• cargo test -p <crate> isolates tests to specific workspace members for rapid iteration
• docker build -t celld-test . executes tests in a CI-identical container environment
• Live-fleet tests require Cloudflare infrastructure and skip by default
• The testing philosophy spans conformance, specification, simulation, and live-fleet layers as documented in docs/testing.md

---

Frequently Asked Questions

Do I need Cloudflare credentials to run celld tests?

No. The standard test suite executes without external services. Only the live-fleet integration layer requires Cloudflare Workers credentials via wrangler, and these tests auto-skip when environment variables are absent.

Why does my local test pass but CI fails?

Most commonly due to missing --locked. Without this flag, Cargo resolves newer dependency versions than those recorded in Cargo.lock. Always use cargo test --all --locked to match CI behavior.

Can I run tests without installing Rust locally?

Yes. The Dockerfile in the repository root provides a complete build environment. Run docker build -t celld-test . to execute the full test suite without any local Rust toolchain.

How do I test only the changes I'm working on?

Use crate-specific filtering: cargo test -p <crate-name>. For even finer granularity, append a test name pattern: cargo test -p ltx my_function runs only tests matching that substring within the ltx crate.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}