bunx vitest vs vitest in Bun Scripts

By Jorge Saud · April 28, 2026

Short one. If bun run test is failing with vitest: command not found even though vitest is clearly in your devDependencies, read on.

What’s Happening

Your package.json probably looks like this:

{
  "scripts": {
    "test": "vitest run"
  }
}

When npm or pnpm runs a script, they prepend node_modules/.bin to PATH before executing. That’s how vitest run resolves to the locally installed binary.

Bun does this too — most of the time. But the behavior isn’t always consistent across Bun versions, shell environments, and CI setups. In some contexts (Docker images, certain CI runners, non-interactive shells), node_modules/.bin doesn’t make it onto PATH, and Bun falls back to the system shell which has no idea what vitest is.

The Fix

Replace the bare binary name with bunx:

{
  "scripts": {
    "test": "bunx vitest run",
    "test:watch": "bunx vitest",
    "test:coverage": "bunx vitest run --coverage"
  }
}

bunx is Bun’s package runner — equivalent to npx for npm or pnpx for pnpm. It resolves and executes the binary from node_modules/.bin explicitly, regardless of what’s on PATH. No ambiguity, no environment dependency.

Why Not Just Install Vitest Globally?

You could — bun add -g vitest — but then you’ve introduced a version dependency on whatever global is installed on each machine. Your CI passes with vitest 3.x, someone runs it locally with vitest 4.x, tests behave differently. bunx always uses the version from the project’s node_modules, which is pinned in bun.lockb.

Why Not Hardcode the Path?

"test": "bun node_modules/.bin/vitest run"

This works but it’s fragile. The path separator is platform-specific, and it’ll break in any project where node_modules lives somewhere other than the project root (monorepos, workspaces). bunx handles all of that for you.

The Pattern

For any CLI tool you run in package.json scripts under Bun, prefer bunx <tool> over bare <tool>. It’s explicit, portable, and always resolves from the local install:

{
  "scripts": {
    "test": "bunx vitest run",
    "lint": "bunx biome check .",
    "typecheck": "bunx tsc --noEmit"
  }
}

The only exception is scripts that are Bun builtins or shell commands — those don’t go through bunx.