Local testing

Hollywood has three local testing layers.

Unit tests

Use a fake executor when the script's command sequence is the contract:

const commands: Command[] = [];

await runAction(publishImage, {
    with: {
        image: "ghcr.io/acme/api",
        tag: "sha-abc123",
        provenance: "false",
    },
    exec: async (file, args, options) => {
        commands.push({ file, args, ...options });
        return { exitCode: 0, stdout: "", stderr: "" };
    },
    fs: { readText: async () => "" },
    log: memoryLog,
    runner: { uidGid: "1001:1001" },
});

This test verifies typed inputs, output shapes, command arguments, and explicit nonzero-exit handling.

Direct library execution

Use nodeExec, nodeFs, and nodeLog when the script should run on the local machine:

await runAction(action, {
  with,
  exec: nodeExec,
  fs: nodeFs,
  log: nodeLog,
  runner: { uidGid: "1001:1001" },
});

Use this mode for scripts that call local tools such as aws, tar, zstd, terraform, or project-specific binaries.

Fast container execution

Install Docker Engine or Docker Desktop, Podman, or Apple container. Select the Docker provider when Docker Desktop uses Docker VMM. Apple container requires Apple silicon and macOS 26 or later:

npx hollywood run gha/go/s3-cache.ts \
  --export s3Cache \
  --provider container \
  --with mode=restore

Hollywood bundles the action, starts one Linux container, and runs the bundle with Node 24. It mounts /github/workspace and creates paths for GITHUB_ENV, GITHUB_EVENT_PATH, GITHUB_OUTPUT, GITHUB_PATH, GITHUB_STATE, and GITHUB_STEP_SUMMARY.

The default image derives from GitHub's digest-pinned Actions runner image. It has native Linux amd64 and arm64 manifests. It is not the GitHub-hosted ubuntu-latest virtual machine, and Hollywood does not invoke the GitHub runner worker.

Provider selection is explicit. Hollywood throws ContainerProviderUnavailableError when the selected executable is absent. It does not detect or use a different runtime.

Use GitHub runner execution when the test must execute the official Runner.Listener and Runner.Worker lifecycle. That mode runs one GitHub-scheduled job and covers action pre and post handlers, state propagation, runner hooks, permissions, caches, artifacts, and job reporting.

Real local services

Use MinIO or LocalStack when the script talks to cloud-shaped APIs. The current local S3 test is gated because it needs a local service:

HOLLYWOOD_RUN_LOCAL_S3=1 HOLLYWOOD_RUN_MINIO=1 \
  npm test -- src/script.test.ts

This test verifies the script against a local implementation of the required service. Run the generated action on GitHub to verify GitHub-managed behavior.

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