test: add a spread test for the npm reentrant bug

The bug is caused by the plugin having state that implicitly needs to be
passed from the 'pull' step to the 'build' step. If both are done in a
single Snapcraft 'run', then it works fine; however, running first 'pull'
and then 'build' separately trigger the issue - a failure on the build
step.

Ref: canonical/craft-parts#844

tests/spread/core24/npm-reentrant/hello.js

@@ -0,0 +1,3 @@
+#!/usr/bin/env node
+
+console.log('hello world');

tests/spread/core24/npm-reentrant/package.json

@@ -0,0 +1,13 @@
+{
+  "name": "npm-hello",
+  "version": "1.0.0",
+  "description": "Testing grounds for snapcraft integration tests",
+  "bin": {
+    "npm-hello": "hello.js"
+  },
+  "scripts": {
+    "npm-hello": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "",
+  "license": "GPL-3.0"
+}

tests/spread/core24/npm-reentrant/snap/snapcraft.yaml

@@ -0,0 +1,15 @@
+name: npm-reentrant
+version: "1.0"
+summary: test the npm plugin
+description: Check that the npm plugin works across snapcraft calls
+
+confinement: strict
+grade: devel
+base: core24
+
+parts:
+  hello:
+    source: .
+    plugin: npm
+    npm-include-node: true
+    npm-node-version: 22.1.0

tests/spread/core24/npm-reentrant/task.yaml

@@ -0,0 +1,11 @@
+summary: Pull, then Build, a Node snap
+
+execute: |
+  snapcraft pull
+  snapcraft build
+  snapcraft pack
+  test -f npm-reentrant*.snap
+
+restore: |
+  snapcraft clean
+  rm -f ./*.snap