node/deps/npm/test/tap/dedupe.js

var test = require("tap").test
  , fs = require("fs")
  , path = require("path")
  , existsSync = fs.existsSync || path.existsSync
  , rimraf = require("rimraf")
  , mr = require("npm-registry-mock")
  , common = require("../common-tap.js")

var EXEC_OPTS = {}

test("dedupe finds the common module and moves it up one level", function (t) {
  setup(function (s) {
    common.npm(
    [
      "install", ".",
      "--registry", common.registry
    ],
    EXEC_OPTS,
    function (err, code) {
      t.ifError(err, "successfully installed directory")
      t.equal(code, 0, "npm install exited with code")
      common.npm(["dedupe"], {}, function (err, code) {
        t.ifError(err, "successfully deduped against previous install")
        t.notOk(code, "npm dedupe exited with code")
        t.ok(existsSync(path.join(__dirname, "dedupe", "node_modules", "minimist")))
        t.ok(!existsSync(path.join(__dirname, "dedupe", "node_modules", "checker")))
        s.close() // shutdown mock registry.
        t.end()
      })
    })
  })
})

function setup (cb) {
  process.chdir(path.join(__dirname, "dedupe"))
  mr({port : common.port}, function (er, s) { // create mock registry.
    rimraf.sync(path.join(__dirname, "dedupe", "node_modules"))
    fs.mkdirSync(path.join(__dirname, "dedupe", "node_modules"))
    cb(s)
  })
}