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Merge pull request #25 from defunctzombie/promisify-callbackify
Add util.promisify and util.callbackify
2 parents 0fe5860 + aafbe16 commit 2c65d29

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‎package.json

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@@ -29,6 +29,7 @@
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"license": "MIT",
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"devDependencies": {
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"airtap": "0.0.6",
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"is-async-supported": "~1.2.0",
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"run-series": "~1.1.4",
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"tape": "~4.9.0"
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},

‎test/browser/callbackify.js

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'use strict';
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var test = require('tape');
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var callbackify = require('../../').callbackify;
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if (typeof Promise === 'undefined') {
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console.log('no global Promise found, skipping callbackify tests');
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return;
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}
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function after (n, cb) {
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var i = 0;
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return function () {
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if (++i === n) cb();
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}
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}
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var values = [
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'hello world',
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null,
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undefined,
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false,
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0,
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{},
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{ key: 'value' },
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function ok() {},
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['array', 'with', 4, 'values'],
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new Error('boo')
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];
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if (typeof Symbol !== 'undefined') {
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values.push(Symbol('I am a symbol'));
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}
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test('util.callbackify resolution value is passed as second argument to callback', function (t) {
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var end = after(values.length * 2, t.end);
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// Test that the resolution value is passed as second argument to callback
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values.forEach(function(value) {
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// Test Promise factory
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function promiseFn() {
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return Promise.resolve(value);
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}
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var cbPromiseFn = callbackify(promiseFn);
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cbPromiseFn(function(err, ret) {
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t.ifError(err);
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t.strictEqual(ret, value, 'cb ' + typeof value);
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end();
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});
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// Test Thenable
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function thenableFn() {
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return {
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then: function(onRes, onRej) {
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onRes(value);
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}
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};
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}
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var cbThenableFn = callbackify(thenableFn);
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cbThenableFn(function(err, ret) {
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t.ifError(err);
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t.strictEqual(ret, value, 'thenable ' + typeof value);
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end();
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});
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});
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});
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test('util.callbackify rejection reason is passed as first argument to callback', function (t) {
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var end = after(values.length * 2, t.end);
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// Test that rejection reason is passed as first argument to callback
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values.forEach(function(value) {
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// test a Promise factory
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function promiseFn() {
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return Promise.reject(value);
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}
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var cbPromiseFn = callbackify(promiseFn);
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cbPromiseFn(function(err, ret) {
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t.strictEqual(ret, undefined, 'cb ' + typeof value);
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if (err instanceof Error) {
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if ('reason' in err) {
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t.ok(!value);
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t.strictEqual(err.message, 'Promise was rejected with a falsy value');
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t.strictEqual(err.reason, value);
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} else {
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t.strictEqual(String(value).slice(-err.message.length), err.message);
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}
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} else {
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t.strictEqual(err, value);
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}
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end();
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});
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// Test Thenable
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function thenableFn() {
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return {
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then: function (onRes, onRej) {
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onRej(value);
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}
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};
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}
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var cbThenableFn = callbackify(thenableFn);
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cbThenableFn(function(err, ret) {
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t.strictEqual(ret, undefined, 'thenable ' + typeof value);
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if (err instanceof Error) {
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if ('reason' in err) {
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t.ok(!value);
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t.strictEqual(err.message, 'Promise was rejected with a falsy value');
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t.strictEqual(err.reason, value);
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} else {
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t.strictEqual(String(value).slice(-err.message.length), err.message);
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}
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} else {
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t.strictEqual(err, value);
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}
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end();
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});
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});
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});
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test('util.callbackify arguments passed to callbackified function are passed to original', function (t) {
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var end = after(values.length, t.end);
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// Test that arguments passed to callbackified function are passed to original
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values.forEach(function(value) {
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function promiseFn(arg) {
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t.strictEqual(arg, value);
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return Promise.resolve(arg);
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}
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var cbPromiseFn = callbackify(promiseFn);
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cbPromiseFn(value, function(err, ret) {
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t.ifError(err);
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t.strictEqual(ret, value);
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end();
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});
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});
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});
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test('util.callbackify `this` binding is the same for callbackified and original', function (t) {
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var end = after(values.length, t.end);
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// Test that `this` binding is the same for callbackified and original
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values.forEach(function(value) {
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var iAmThis = {
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fn: function(arg) {
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t.strictEqual(this, iAmThis);
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return Promise.resolve(arg);
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},
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};
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iAmThis.cbFn = callbackify(iAmThis.fn);
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iAmThis.cbFn(value, function(err, ret) {
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t.ifError(err);
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t.strictEqual(ret, value);
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t.strictEqual(this, iAmThis);
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end();
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});
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});
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});
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test('util.callbackify non-function inputs throw', function (t) {
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// Verify that non-function inputs throw.
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['foo', null, undefined, false, 0, {}, typeof Symbol !== 'undefined' ? Symbol() : undefined, []].forEach(function(value) {
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t.throws(
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function() { callbackify(value); },
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'The "original" argument must be of type Function'
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);
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});
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t.end();
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});

‎test/browser/index.js

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require('./inspect');
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require('./is');
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require('./promisify');
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require('./callbackify');

‎test/browser/promisify.js

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var promisify = require('../../').promisify;
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var test = require('tape');
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var hasSymbol = typeof Symbol !== 'undefined';
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if (typeof Promise === 'undefined') {
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console.log('no global Promise found, skipping promisify tests');
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return;
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}
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var callbacker = function (arg, cb) {
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setTimeout(function () {
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if (typeof arg === 'string')
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cb(null, arg.toUpperCase());
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else cb(new TypeError('incorrect type'));
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}, 5);
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}
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var promiser = promisify(callbacker);
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test('util.promisify resolves', function (t) {
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var promise = promiser(__filename);
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t.ok(promise instanceof Promise);
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promise.then(function (value) {
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t.deepEqual(value, __filename.toUpperCase());
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t.end();
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});
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});
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test('util.promisify rejects', function (t) {
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var promise = promiser(42);
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promise.catch(function (error) {
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t.equal(error.message, 'incorrect type');
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t.end();
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});
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});
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test('util.promisify custom', { skip: !hasSymbol }, function (t) {
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function fn() {}
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function promisifedFn() {}
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fn[promisify.custom] = promisifedFn;
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t.strictEqual(promisify(fn), promisifedFn);
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t.strictEqual(promisify(promisify(fn)), promisifedFn);
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t.end();
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});
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test('util.promisify custom of invalid type', { skip: !hasSymbol }, function (t) {
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function fn2() {}
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fn2[promisify.custom] = 42;
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t.throws(
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function () { promisify(fn2); },
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/must be of type Function/
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);
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t.end();
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});
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test('util.promisify multiple callback values', function (t) {
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function fn5(callback) {
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callback(null, 'foo', 'bar');
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}
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promisify(fn5)().then(function (value) {
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t.strictEqual(value, 'foo');
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t.end();
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});
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});
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test('util.promisify no callback success value', function (t) {
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function fn6(callback) {
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callback(null);
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}
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promisify(fn6)().then(function (value) {
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t.strictEqual(value, undefined);
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t.end();
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});
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});
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test('util.promisify no callback arguments at all', function (t) {
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function fn7(callback) {
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callback();
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}
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promisify(fn7)().then(function (value) {
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t.strictEqual(value, undefined);
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t.end();
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});
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});
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test('util.promisify passing arguments', function (t) {
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function fn8(err, val, callback) {
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callback(err, val);
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}
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promisify(fn8)(null, 42).then(function (value) {
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t.strictEqual(value, 42);
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t.end();
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});
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});
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test('util.promisify passing arguments (rejects)', function (t) {
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function fn9(err, val, callback) {
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callback(err, val);
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}
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promisify(fn9)(new Error('oops'), null).catch(function (err) {
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t.strictEqual(err.message, 'oops');
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t.end();
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});
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});
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test('util.promisify chain', function (t) {
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function fn9(err, val, callback) {
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callback(err, val);
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}
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Promise.resolve()
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.then(function () { return promisify(fn9)(null, 42); })
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.then(function (value) {
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t.strictEqual(value, 42);
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t.end();
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});
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});
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test('util.promisify keeps correct `this`', function (t) {
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var o = {};
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var fn10 = promisify(function(cb) {
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cb(null, this === o);
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});
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o.fn = fn10;
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o.fn().then(function(val) {
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t.ok(val);
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t.end();
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});
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});
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test('util.promisify calling callback multiple times', function (t) {
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var err = new Error('Should not have called the callback with the error.');
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var stack = err.stack;
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var fn11 = promisify(function(cb) {
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cb(null);
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cb(err);
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});
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Promise.resolve()
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.then(function () { return fn11(); })
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.then(function () { return Promise.resolve(); })
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.then(function () {
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t.strictEqual(stack, err.stack);
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t.end();
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});
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});
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// Can't do this without Symbol() unfortunately
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test('util.promisify promisifying a promisified function', { skip: !hasSymbol }, function (t) {
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function c() { }
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var a = promisify(function() { });
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var b = promisify(a);
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t.notStrictEqual(c, a);
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t.strictEqual(a, b);
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t.end();
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});
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test('util.promisify sync throw becomes rejection', function (t) {
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var errToThrow;
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var thrower = promisify(function(a, b, c, cb) {
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errToThrow = new Error();
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throw errToThrow;
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});
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thrower(1, 2, 3)
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.then(t.fail)
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.then(t.fail, function (e) {
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t.strictEqual(e, errToThrow);
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t.end();
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});
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});
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test('util.promisify callback and sync throw', function (t) {
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var err = new Error();
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var a = promisify(function (cb) { cb(err) })();
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var b = promisify(function () { throw err; })();
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Promise.all([
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a.then(t.fail, function(e) {
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t.strictEqual(err, e);
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}),
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b.then(t.fail, function(e) {
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t.strictEqual(err, e);
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})
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]).then(function () {
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t.end();
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});
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});
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test('util.promisify throws for incorrect argument types', function (t) {
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var array = [undefined, null, true, 0, 'str', {}, []];
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if (typeof Symbol !== 'undefined') array.push(Symbol());
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array.forEach(function (input) {
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t.throws(
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function () { promisify(input); },
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'The "original" argument must be of type Function'
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);
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});
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t.end();
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});

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