test: add workspace monorepo bun install test

tests/install_test/workspaces.sh

@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+bun_path="$1"
+workdir="$(mktemp -d)"
+trap 'rm -rf "${workdir}"' EXIT
+
+mkdir -p "${workdir}/packages/pkg-a" "${workdir}/packages/pkg-b"
+
+cat >"${workdir}/package.json" <<'JSON'
+{
+  "name": "workspace-root",
+  "private": true,
+  "workspaces": ["packages/*"]
+}
+JSON
+
+cat >"${workdir}/packages/pkg-a/package.json" <<'JSON'
+{
+  "name": "@workspace/pkg-a",
+  "version": "1.0.0",
+  "main": "index.js"
+}
+JSON
+
+cat >"${workdir}/packages/pkg-a/index.js" <<'JS'
+module.exports = { value: 42 };
+JS
+
+cat >"${workdir}/packages/pkg-b/package.json" <<'JSON'
+{
+  "name": "@workspace/pkg-b",
+  "version": "1.0.0",
+  "dependencies": {
+    "@workspace/pkg-a": "workspace:*"
+  },
+  "scripts": {
+    "check": "bun -e \"const { value } = require('@workspace/pkg-a'); if (value !== 42) process.exit(1)\""
+  }
+}
+JSON
+
+"${bun_path}" install --cwd "${workdir}" >/dev/null
+rm -rf "${workdir}/node_modules" "${workdir}/packages/pkg-b/node_modules"
+"${bun_path}" install --cwd "${workdir}" --frozen-lockfile >/dev/null
+"${bun_path}" run --cwd "${workdir}/packages/pkg-b" check >/dev/null