tests: test-fs-exists ported from node.js

tests/test-fs-exists.lua

@@ -0,0 +1,46 @@
+--[[
+
+Copyright 2012 The Luvit Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License")
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS-IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+--]]
+
+require("helper")
+
+local FS = require('fs')
+local Path = require('path')
+
+local f = __filename
+local exists
+local doesNotExist
+
+-- TODO: Is it OK that this callback signature is different from node.js,
+--       which is function(exists)?
+FS.exists(f, function(err, y)
+  exists = y
+--  p("exists=" .. tostring(exists))
+end)
+
+FS.exists(f .. '-NO', function(err, y)
+  doesNotExist = y
+--  p("doesNotExist=" .. tostring(doesNotExist))
+end)
+
+assert(FS.existsSync(f))
+assert(not FS.existsSync(f .. '-NO'))
+
+process:on('exit', function()
+  assert(exists == true)
+  assert(doesNotExist == false)
+end)