install/actions: Check installability of modules from shrinkwrap

Modules that came into the tree via shrinkwrap won't have had this
determined in advance so we check here and take advantage of the
optional rollback semantics to skip them.

Plus if it was a regular dependency we can just fail out now instead of
trying and failing to install the dep.

Fixes: #13394
PR-URL: #13692
Credit: @iarna
Reviewed-By: @zkat

lib/install/actions.js

@@ -10,6 +10,7 @@ var failedDependency = require('./deps.js').failedDependency
 var moduleName = require('../utils/module-name.js')
 var buildPath = require('./build-path.js')
 var reportOptionalFailure = require('./report-optional-failure.js')
+var isInstallable = require('./validate-args.js').isInstallable
 
 var actions = {}
 
@@ -45,7 +46,23 @@ Object.keys(actions).forEach(function (actionName) {
       if (!pkg.commit) pkg.commit = []
       pkg.commit.push(action.commit)
     }
-    return action(top, buildpath, pkg, log, andFinishTracker(log, andAddParentToErrors(pkg.parent, andHandleOptionalDepErrors(pkg, next))))
+    if (pkg.knownInstallable) {
+      return thenRunAction()
+    } else {
+      return isInstallable(pkg.package, iferr(andDone(next), andMarkInstallable(thenRunAction)))
+    }
+    function andMarkInstallable (cb) {
+      return function () {
+        pkg.knownInstallable = true
+        cb()
+      }
+    }
+    function thenRunAction () {
+      action(top, buildpath, pkg, log, andDone(next))
+    }
+    function andDone (cb) {
+      return andFinishTracker(log, andAddParentToErrors(pkg.parent, andHandleOptionalDepErrors(pkg, cb)))
+    }
   }
 })
 

test/tap/shrinkwrap-optional-platform.js

@@ -0,0 +1,96 @@
+'use strict'
+var path = require('path')
+var test = require('tap').test
+var Tacks = require('tacks')
+var File = Tacks.File
+var Dir = Tacks.Dir
+var extend = Object.assign || require('util')._extend
+var common = require('../common-tap.js')
+
+var basedir = path.join(__dirname, path.basename(__filename, '.js'))
+var testdir = path.join(basedir, 'testdir')
+var cachedir = path.join(basedir, 'cache')
+var globaldir = path.join(basedir, 'global')
+var tmpdir = path.join(basedir, 'tmp')
+
+var conf = {
+  cwd: testdir,
+  env: extend(extend({}, process.env), {
+    npm_config_cache: cachedir,
+    npm_config_tmp: tmpdir,
+    npm_config_prefix: globaldir,
+    npm_config_registry: common.registry,
+    npm_config_loglevel: 'warn'
+  })
+}
+
+var fixture = new Tacks(Dir({
+  cache: Dir(),
+  global: Dir(),
+  tmp: Dir(),
+  testdir: Dir({
+    mod1: Dir({
+      'package.json': File({
+        name: 'mod1',
+        version: '1.0.0',
+        scripts: {
+
+        },
+        os: ['nosuchos']
+      })
+    }),
+    'npm-shrinkwrap.json': File({
+      name: 'shrinkwrap-optional-platform',
+      version: '1.0.0',
+      dependencies: {
+        mod1: {
+          version: '1.0.0',
+          from: 'mod1',
+          resolved: 'file:mod1',
+          optional: true
+        }
+      }
+    }),
+    'package.json': File({
+      name: 'shrinkwrap-optional-platform',
+      version: '1.0.0',
+      optionalDependencies: {
+        mod1: 'file:mod1'
+      },
+      description: 'x',
+      repository: 'x',
+      license: 'Artistic-2.0'
+    })
+  })
+}))
+
+function setup () {
+  cleanup()
+  fixture.create(basedir)
+}
+
+function cleanup () {
+  fixture.remove(basedir)
+}
+
+test('setup', function (t) {
+  setup()
+  t.done()
+})
+
+test('example', function (t) {
+  common.npm(['install'], conf, function (err, code, stdout, stderr) {
+    if (err) throw err
+    t.is(code, 0, 'install ran ok')
+    t.comment(stdout.trim())
+    t.comment(stderr.trim())
+    t.notMatch(stderr, /Exit status 1/, 'did not try to install opt dep')
+    t.done()
+  })
+})
+
+test('cleanup', function (t) {
+  cleanup()
+  t.done()
+})
+