feat: pnpm-style symlinking (#636) (#657)

* chore: add repro test for pnpm-style symlinking

* chore: show that it works with esbuild-based bundlers

Co-authored-by: Netlify Team Account 1 <netlify-team-account-1@users.noreply.github.com>
Co-authored-by: kodiakhq[bot] <49736102+kodiakhq[bot]@users.noreply.github.com>

tests/fixtures/node-module-symlinks/function.js

@@ -0,0 +1,3 @@
+const isEven = require('is-even')
+
+module.exports = (number) => (isEven(number) ? `${number} is even` : `${number} is odd`)

tests/fixtures/node-module-symlinks/package.json

@@ -0,0 +1,5 @@
+{
+  "dependencies": {
+    "is-even": "^1.0.0"
+  }
+}

tests/main.js

@@ -1976,3 +1976,14 @@ test('Creates a manifest file with the list of created functions if the `manifes
     t.is(fn.path, file.path)
   })
 })
+
+testBundlers('Correctly follows node_modules via symlink', [ESBUILD, ESBUILD_ZISI], async (bundler, t) => {
+  const { tmpDir } = await zipNode(t, 'node-module-symlinks', {
+    opts: { config: { '*': { nodeBundler: bundler } } },
+  })
+
+  // eslint-disable-next-line import/no-dynamic-require, node/global-require
+  const isEven = require(`${tmpDir}/function`)
+  // eslint-disable-next-line no-magic-numbers
+  t.is(isEven(10), '10 is even')
+})