Convert shrinkwrap test script from bash to Node.

Works better on Windows.

test/packages/npm-test-shrinkwrap/package.json

@@ -8,6 +8,6 @@
     "minimatch": "~0.1.0"
   },
   "scripts": {
-    "test": "bash test.sh"
+    "test": "node test.js"
   }
 }

test/packages/npm-test-shrinkwrap/test.js

@@ -0,0 +1,19 @@
+var path = require("path")
+var assert = require("assert")
+
+process.env.npm_config_prefix = process.cwd()
+delete process.env.npm_config_global
+delete process.env.npm_config_depth
+
+var npm = path.resolve(process.env.npm_config_prefix, "../../npm")
+
+require("child_process").exec(npm + " ls --json", {
+    stdio: "pipe", env: process.env, cwd: process.cwd() },
+    function (err, stdout, stderr) {
+  if (err) throw err
+
+  var actual = JSON.parse(stdout).dependencies
+  var expected = require("./npm-shrinkwrap.json").dependencies
+
+  assert.deepEqual(actual, expected)
+})