Building

What the build step does

The build step transforms TypeScript source code into distributable JavaScript. The raw .ts files in src/ can’t be published or executed directly by Node.js — they need to be compiled to .js, and type declarations (.d.ts) need to be generated so consumers get autocompletion.

tsup handles this. It’s a TypeScript bundler powered by esbuild, which compiles orders of magnitude faster than the standard TypeScript compiler (tsc). tsup also handles ESM output correctly without extra configuration and generates both JavaScript and type declarations in a single step.

The build produces two entry points:

• dist/cli.js — the CLI binary. This is what the bin field in package.json points to, and what runs when a user types semtest. It contains the Commander command definitions and orchestrates the full pipeline.
• dist/index.js — the public API. This is what consumers get when they import { defineConfig } from "@thulanek/semtest-runner". It re-exports the config helper and types for programmatic use.

Code splitting is enabled, so shared modules (like the config schema, which both entry points need) are bundled into a separate chunk and imported by both — no duplication.

tsup configuration

The config lives at packages/semtest-runner/tsup.config.ts:

import { defineConfig } from "tsup";

export default defineConfig({
  entry: ["src/cli.ts", "src/index.ts"],
  format: ["esm"],
  dts: true,
  clean: true,
  target: "node20",
  splitting: true,
});

Option	Value	Purpose
entry	cli.ts, index.ts	Two entry points — CLI binary and public API
format	esm	ESM-only output (no CJS)
dts	true	Generates .d.ts declaration files
clean	true	Clears dist/ before each build
target	node20	Minimum Node version
splitting	true	Code-splits shared modules between entry points

TypeScript configuration

Key compiler options from packages/semtest-runner/tsconfig.json:

Option	Value
target	ES2022
module	ESNext
moduleResolution	bundler
strict	true
declaration	true
isolatedModules	true

Turbo pipeline

The root turbo.json defines three tasks:

{
  "tasks": {
    "build": {
      "dependsOn": ["^build"],
      "outputs": ["dist/**"]
    },
    "dev": {
      "cache": false,
      "persistent": true
    },
    "test": {
      "dependsOn": ["build"]
    }
  }
}

• build: Topologically ordered — dependencies build before dependents. Cached by dist/** output.
• dev: Not cached, runs persistently (watch mode).
• test: Runs after build completes.

Build commands

# Build everything
pnpm turbo run build

# Build only the main package
pnpm turbo run build --filter=@thulanek/semtest-runner

# Watch mode (dev)
pnpm turbo run dev --filter=@thulanek/semtest-runner