Add more tests

test/async.js

@@ -1,14 +1,10 @@
 'use strict';
 
 const metatests = require('metatests');
-const {
-  toBool,
-  timeout,
-  delay,
-  timeoutify,
-  throttle,
-  debounce,
-} = require('..');
+const metautil = require('..');
+const { toBool, timeout, delay } = metautil;
+const { timeoutify, throttle, debounce } = metautil;
+const { callbackify, asyncify, promisify } = metautil;
 
 metatests.test('Async: toBool', async (test) => {
   const success = await Promise.resolve('success').then(...toBool);
@@ -175,3 +171,68 @@ metatests.test('Async: debounce without arguments', (test) => {
   debouncedFn();
   test.strictSame(count, 0);
 });
+
+metatests.test('Callbackify: Promise to callback-last', (test) => {
+  const promiseReturning = () => Promise.resolve('result');
+  const asyncFn = callbackify(promiseReturning);
+
+  asyncFn((err, value) => {
+    if (err) {
+      test.error(err, 'must not throw');
+    }
+    test.strictSame(value, 'result');
+    test.end();
+  });
+});
+
+metatests.test('Asyncify: sync function to callback-last', (test) => {
+  const fn = (par) => par;
+  const asyncFn = asyncify(fn);
+
+  asyncFn('result', (err, value) => {
+    if (err) {
+      test.error(err, 'must not throw');
+    }
+    test.strictSame(value, 'result');
+    test.end();
+  });
+});
+
+metatests.test('Promisify: callback-last to Promise', async (test) => {
+  const id = 100;
+  const data = { key: 'value' };
+
+  const getDataAsync = (dataId, callback) => {
+    test.strictSame(dataId, id);
+    callback(null, data);
+  };
+
+  const getDataPromise = promisify(getDataAsync);
+
+  try {
+    const result = await getDataPromise(id);
+    test.strictSame(result, data);
+    test.end();
+  } catch (err) {
+    test.error(err, 'must not throw');
+  }
+});
+
+metatests.test('Promisify: callback-last to Promise throw', async (test) => {
+  const id = 100;
+
+  const getDataAsync = (dataId, callback) => {
+    test.strictSame(dataId, id);
+    callback(new Error('Data not found'));
+  };
+
+  const getDataPromise = promisify(getDataAsync);
+
+  try {
+    const result = await getDataPromise(id);
+    test.notOk(result);
+  } catch (err) {
+    test.ok(err);
+    test.end();
+  }
+});