var promisify = require("promisify-node");
var fs = promisify("fs");
// This function has been identified as an asynchronous function so it has
// been automatically wrapped.
fs.readFile("/etc/passwd").then(function(contents) {
  console.log(contents);
});

var promisify = require("promisify-node");
function async(callback) {
  callback(null, true);
}
// Convert the function to return a Promise.
var wrap = promisify(async);
// Invoke the newly wrapped function.
wrap().then(function(value) {
  console.log(value === true);
});

var promisify = require("promisify-node");
var myObj = {
  myMethod: function(a, b, cb) {
    cb(a, b);
  }
};
// No need to return anything as the methods will be replaced on the object.
promisify(myObj);
// Intentionally cause a failure by passing an object and inspect the message.
myObj.myMethod({ msg: "Failure!" }, null).then(null, function(err) {
  console.log(err.msg);
});

var promisify = require("promisify-node");
var myObj = {
  myMethod: function(a, b, cb) {
    cb(a, b);
  }
};
// Store the original method to check later
var originalMethod = myObj.myMethod;
// Now store the result, since the 'true' value means it won't mutate 'myObj'.
var promisifiedObj = promisify(myObj, undefined, true);
// Intentionally cause a failure by passing an object and inspect the message.
promisifiedObj.myMethod({ msg: "Failure!" }, null).then(null, function(err) {
  console.log(err.msg);
});
// The original method is still intact
assert(myObj.myMethod === originalMethod);
assert(promisifiedObj.myMethod !== myObj.myMethod);