install: fix checking for optional dep

Fixes: https://npm.community/t/2569

Credit: @larsgw
Reviewed-By: @iarna

lib/install/is-only-dev.js

@@ -28,6 +28,7 @@ function andIsOnlyDev (name, seen) {
       return isDev && !isProd
     } else {
       if (seen.has(req)) return true
+      seen = new Set(seen)
       seen.add(req)
       return isOnlyDev(req, seen)
     }

lib/install/is-only-optional.js

@@ -10,6 +10,7 @@ function isOptional (node, seen) {
   if (seen.has(node) || node.requiredBy.length === 0) {
     return false
   }
+  seen = new Set(seen)
   seen.add(node)
   const swOptional = node.fromShrinkwrap && node.package._optional
   return node.requiredBy.every(function (req) {

test/tap/install-dep-classification.js

@@ -0,0 +1,167 @@
+'use strict'
+const path = require('path')
+const test = require('tap').test
+const Tacks = require('tacks')
+const File = Tacks.File
+const Dir = Tacks.Dir
+const common = require('../common-tap.js')
+const fs = require('fs')
+
+const basedir = path.join(__dirname, path.basename(__filename, '.js'))
+const testdir = path.join(basedir, 'testdir')
+const cachedir = path.join(basedir, 'cache')
+const globaldir = path.join(basedir, 'global')
+const tmpdir = path.join(basedir, 'tmp')
+const optionaldir = path.join(testdir, 'optional')
+const devdir = path.join(testdir, 'dev')
+
+const env = common.newEnv().extend({
+  npm_config_cache: cachedir,
+  npm_config_tmp: tmpdir,
+  npm_config_prefix: globaldir,
+  npm_config_registry: common.registry,
+  npm_config_loglevel: 'error'
+})
+
+const fixture = new Tacks(Dir({
+  cache: Dir(),
+  global: Dir(),
+  tmp: Dir(),
+  testdir: Dir({
+    'a-1.0.0.tgz': File(Buffer.from(
+      '1f8b0800000000000003edcfc10e82300c0660ce3ec5d2b38e4eb71d789b' +
+      '010d41e358187890f0ee56493c71319218937d977feb9aa50daebab886f2' +
+      'b0a43cc7ce671b4344abb558ab3f2934223b198b4a598bdcc707a38f9c5b' +
+      '0fb2668c83eb79946fff597611effc131378772528c0c11e6ed4c7b6f37c' +
+      '53122572a5a640be265fb514a198a0e43729f3f2f06a9043738779defd7a' +
+      '89244992e4630fd69e456800080000',
+      'hex'
+    )),
+    'b-1.0.0.tgz': File(Buffer.from(
+      '1f8b08000000000000032b484cce4e4c4fd52f80d07a59c5f9790c540606' +
+      '06066626260ad8c4c1c0d85c81c1d8d4ccc0d0d0cccc00a80ec830353103' +
+      'd2d4760836505a5c925804740aa5e640bca200a78708a856ca4bcc4d55b2' +
+      '524a52d2512a4b2d2acecccf03f20cf50cf40c946ab906da79a360148c82' +
+      '51300a680400106986b400080000',
+      'hex'
+    )),
+    dev: Dir({
+      'package.json': File({
+        name: 'dev',
+        version: '1.0.0',
+        devDependencies: {
+          example: '../example-1.0.0.tgz'
+        }
+      })
+    }),
+    'example-1.0.0.tgz': File(Buffer.from(
+      '1f8b0800000000000003ed8fc10ac2300c8677f62946cedaa5d8f5e0db64' +
+      '5b1853d795758a38f6ee4607e261370722f4bbfce5cb4f493c9527aa39f3' +
+      '73aa63e85cb23288688d4997fc136d304df6b945adad45e9c923375a72ed' +
+      '4596b884817a59e5db7fe65bd277fe0923386a190ec0376afd99610b57ee' +
+      '43d339715aa14231157b7615bbb2e100871148664a65b47b15d450dfa554' +
+      'ccb2f890d3b4f9f57d9148241259e60112d8208a00080000',
+      'hex'
+    )),
+    optional: Dir({
+      'package.json': File({
+        name: 'optional',
+        version: '1.0.0',
+        optionalDependencies: {
+          example: '../example-1.0.0.tgz'
+        }
+      })
+    })
+  })
+}))
+
+function setup () {
+  cleanup()
+  fixture.create(basedir)
+}
+
+function cleanup () {
+  fixture.remove(basedir)
+}
+
+test('setup', function (t) {
+  setup()
+  return common.fakeRegistry.listen()
+})
+
+test('optional dependency identification', function (t) {
+  return common.npm(['install', '--no-optional'], {cwd: optionaldir, env}).then(([code, stdout, stderr]) => {
+    t.is(code, 0, 'no error code')
+    t.is(stderr, '', 'no error output')
+    t.notOk(fs.existsSync(path.join(optionaldir, 'node_modules')), 'did not install anything')
+    t.similar(JSON.parse(fs.readFileSync(path.join(optionaldir, 'package-lock.json'), 'utf8')), {
+      dependencies: {
+        a: {
+          version: 'file:../a-1.0.0.tgz',
+          optional: true
+        },
+        b: {
+          version: 'file:../b-1.0.0.tgz',
+          optional: true
+        },
+        example: {
+          version: '1.0.0',
+          optional: true
+        }
+      }
+    }, 'locks dependencies as optional')
+  })
+})
+
+test('development dependency identification', function (t) {
+  return common.npm(['install', '--only=prod'], {cwd: devdir, env}).then(([code, stdout, stderr]) => {
+    t.is(code, 0, 'no error code')
+    t.is(stderr, '', 'no error output')
+    t.notOk(fs.existsSync(path.join(devdir, 'node_modules')), 'did not install anything')
+    t.similar(JSON.parse(fs.readFileSync(path.join(devdir, 'package-lock.json'), 'utf8')), {
+      dependencies: {
+        a: {
+          version: 'file:../a-1.0.0.tgz',
+          dev: true
+        },
+        b: {
+          version: 'file:../b-1.0.0.tgz',
+          dev: true
+        },
+        example: {
+          version: '1.0.0',
+          dev: true
+        }
+      }
+    }, 'locks dependencies as dev')
+  })
+})
+
+test('default dependency identification', function (t) {
+  return common.npm(['install'], {cwd: optionaldir, env}).then(([code, stdout, stderr]) => {
+    t.is(code, 0, 'no error code')
+    t.is(stderr, '', 'no error output')
+    t.similar(JSON.parse(fs.readFileSync(path.join(optionaldir, 'package-lock.json'), 'utf8')), {
+      dependencies: {
+        a: {
+          version: 'file:../a-1.0.0.tgz',
+          optional: true
+        },
+        b: {
+          version: 'file:../b-1.0.0.tgz',
+          optional: true
+        },
+        example: {
+          version: '1.0.0',
+          optional: true
+        }
+      }
+    }, 'locks dependencies as optional')
+  })
+})
+
+test('cleanup', function (t) {
+  common.fakeRegistry.close()
+  cleanup()
+  t.done()
+})