Add test for npm shrinkwrap compatibility

package.json

@@ -40,6 +40,7 @@
     "eslint-config-standard": "4.4.0",
     "eslint-plugin-standard": "1.3.1",
     "nixt": "0.5.0",
+    "npm": "3.6.0",
     "sepia": "2.0.1",
     "tap-spec": "4.1.1",
     "tape": "4.4.0",

test/index.js

@@ -147,3 +147,19 @@ test('tarballs (is-array-1.0.1.tgz)', function (t) {
   }, t.end)
 })
 
+test('shrinkwrap compatibility', function (t) {
+  prepare()
+  fs.writeFileSync('package.json',
+    JSON.stringify({ dependencies: { rimraf: '*' } }),
+    'utf-8')
+
+  install({ input: ['rimraf@2.5.1'], flags: { quiet: true } })
+  .then(function () {
+    var npm = JSON.stringify(require.resolve('npm/bin/npm-cli.js'))
+    require('child_process').execSync('node ' + npm + ' shrinkwrap')
+    var wrap = JSON.parse(fs.readFileSync('npm-shrinkwrap.json', 'utf-8'))
+    t.ok(wrap.dependencies.rimraf.version === '2.5.1',
+      'npm shrinkwrap is successful')
+    t.end()
+  }, t.end)
+})