feat: allow to link a directory with no manifest (#3695)

close #3691

.changeset/fluffy-olives-check.md

@@ -0,0 +1,5 @@
+---
+"@pnpm/local-resolver": minor
+---
+
+Allow to link a directory that has no manifest file.

packages/local-resolver/src/index.ts

@@ -1,3 +1,5 @@
+import { existsSync } from 'fs'
+import path from 'path'
 import PnpmError from '@pnpm/error'
 import gfs from '@pnpm/graceful-fs'
 import { readProjectManifestOnly } from '@pnpm/read-project-manifest'
@@ -50,14 +52,22 @@ export default async function resolveLocal (
   try {
     localDependencyManifest = await readProjectManifestOnly(spec.fetchSpec) as DependencyManifest
   } catch (internalErr) {
+    if (!existsSync(spec.fetchSpec)) {
+      throw new PnpmError('LINKED_PKG_DIR_NOT_FOUND',
+        `Could not install from "${spec.fetchSpec}" as it does not exist.`)
+    }
     switch (internalErr.code) {
     case 'ENOTDIR': {
       throw new PnpmError('NOT_PACKAGE_DIRECTORY',
         `Could not install from "${spec.fetchSpec}" as it is not a directory.`)
     }
+    case 'ERR_PNPM_NO_IMPORTER_MANIFEST_FOUND':
     case 'ENOENT': {
-      throw new PnpmError('DIRECTORY_HAS_NO_PACKAGE_JSON',
-        `Could not install from "${spec.fetchSpec}" as it does not contain a package.json file.`)
+      localDependencyManifest = {
+        name: path.basename(spec.fetchSpec),
+        version: '0.0.0',
+      }
+      break
     }
     default: {
       throw internalErr

packages/local-resolver/test/index.ts

@@ -98,14 +98,11 @@ test('fail when resolving tarball specified with the link: protocol', async () =
 })
 
 test('fail when resolving from not existing directory', async () => {
-  try {
-    const wantedDependency = { pref: 'link:./dir-does-not-exist' }
-    await resolveFromLocal(wantedDependency, { projectDir: __dirname })
-    fail()
-  } catch (err) {
-    expect(err).toBeDefined()
-    expect(err.code).toEqual('ERR_PNPM_NO_IMPORTER_MANIFEST_FOUND')
-  }
+  const wantedDependency = { pref: 'link:./dir-does-not-exist' }
+  const projectDir = __dirname
+  await expect(
+    resolveFromLocal(wantedDependency, { projectDir })
+  ).rejects.toThrow(`Could not install from "${path.join(projectDir, 'dir-does-not-exist')}" as it does not exist.`)
 })
 
 test('throw error when the path: protocol is used', async () => {

packages/supi/test/install/local.ts

@@ -47,6 +47,18 @@ test('local file', async () => {
   })
 })
 
+test('local directory with no package.json', async () => {
+  const project = prepareEmpty()
+  await fs.mkdir('pkg')
+  await fs.writeFile('pkg/index.js', 'hello', 'utf8')
+
+  const manifest = await addDependenciesToPackage({}, ['file:./pkg'], await testDefaults())
+
+  const expectedSpecs = { pkg: 'link:pkg' }
+  expect(manifest.dependencies).toStrictEqual(expectedSpecs)
+  await project.has('pkg')
+})
+
 test('local file via link:', async () => {
   const project = prepareEmpty()
   await copyFixture('local-pkg', path.resolve('..', 'local-pkg'))