PoolPlus: Add Promise support to pool.sync()

Author: nwoltman

README.md

@@ -242,7 +242,7 @@ and perform queries and transactions using promises.
         * [.raw(sql)](#PoolPlus+raw) ⇒ <code>Object</code>
         * [.basicTable(name)](#PoolPlus+basicTable) ⇒ <code>[MySQLTable](#MySQLTable)</code>
         * [.defineTable(name, schema, [migrationStrategy])](#PoolPlus+defineTable) ⇒ <code>[MySQLTable](#MySQLTable)</code>
-        * [.sync(cb)](#PoolPlus+sync) ⇒ <code>void</code>
+        * [.sync([cb])](#PoolPlus+sync) ⇒ <code>Promise</code>
         * [.pquery(sql, [values], [cb])](#PoolPlus+pquery) ⇒ <code>Promise</code>
         * [.transaction(trxnHandler)](#PoolPlus+transaction) ⇒ <code>Promise</code>
     * _inner_
@@ -355,7 +355,7 @@ const userTable = pool.defineTable('user', {
 
 <a name="PoolPlus+sync"></a>
 
-### poolPlus.sync(cb) ⇒ <code>void</code>
+### poolPlus.sync([cb]) ⇒ <code>Promise</code>
 Syncs the defined tables to the database by creating new tables and dropping
 or migrating existing tables (depending on the migration setting).
 
@@ -367,16 +367,28 @@ Always keep a backup of your database so you can restore it to the latest workin
 
 | Param | Type | Description |
 |:--- |:--- |:--- |
-| cb | <code>function</code> | A callback that is called once all defined table schemas have been synced to the     database. If an error occured, the first argument passed to the callback will be the error object. |
+| [cb] | <code>function</code> | A callback that is called once all defined table schemas have been synced to the     database. If an error occured, the first argument passed to the callback will be the error object. |
 
-**Example**:
+**Returns**: <code>?Promise</code> - If `cb` is not provided, a promise will be returned.
+
+**Example**: With a callback
 ```js
 pool.sync((err) => {
   if (err) throw err;
   // Now do something such as start an HTTP server
 });
 ```
 
+**Example**: With a promise
+```js
+pool.sync()
+  .then(() => {
+    // Success
+  }, (err) => {
+    // Error
+  });
+```
+
 
 ---
 

lib/PoolPlus.js

@@ -152,21 +152,41 @@ class PoolPlus extends Pool {
    * __Warning:__ If an error occurs while syncing, the database will be in an unknown state.
    * Always keep a backup of your database so you can restore it to the latest working state.
    *
-   * @param {function} cb - A callback that is called once all defined table schemas have been synced to the
+   * @param {function} [cb] - A callback that is called once all defined table schemas have been synced to the
    *     database. If an error occured, the first argument passed to the callback will be the error object.
-   * @returns {void}
+   * @returns {?Promise} If `cb` is not provided, a promise will be returned.
    *
-   * @example
+   * @example <caption>With a callback</caption>
    * pool.sync((err) => {
    *   if (err) throw err;
    *   // Now do something such as start an HTTP server
    * });
+   *
+   * @example <caption>With a promise</caption>
+   * pool.sync()
+   *   .then(() => {
+   *     // Success
+   *   }, (err) => {
+   *     // Error
+   *   });
    */
-  sync(cb) {
+  sync(cb) { // eslint-disable-line consistent-return
+    if (!cb) {
+      return new Promise((resolve, reject) => {
+        this.sync(err => {
+          if (err) {
+            reject(err);
+          } else {
+            resolve();
+          }
+        });
+      });
+    }
+
     var tablesRemaining = this._tables.size;
     if (!tablesRemaining) {
       process.nextTick(cb);
-      return;
+      return; // eslint-disable-line consistent-return
     }
 
     var error = null;

test/unit/PoolPlus.test.js

@@ -177,6 +177,12 @@ describe('PoolPlus', () => {
       });
     });
 
+    it('should return a promise if no callback is provided', () => {
+      const promise = pool.sync();
+      promise.should.be.an.instanceOf(Promise);
+      return promise;
+    });
+
 
     describe('if an error occured getting a connection', () => {
 
@@ -200,6 +206,12 @@ describe('PoolPlus', () => {
         });
       });
 
+      it('should reject the returned promise with an error', () => {
+        return pool.sync().catch(err => {
+          err.should.equal(error);
+        });
+      });
+
     });
 
 
@@ -222,6 +234,12 @@ describe('PoolPlus', () => {
         });
       });
 
+      it('should reject the returned promise with an error', () => {
+        return pool.sync().catch(err => {
+          err.should.equal(error);
+        });
+      });
+
     });
 
 
@@ -247,6 +265,12 @@ describe('PoolPlus', () => {
         });
       });
 
+      it('should reject the returned promise with an error', () => {
+        return pool.sync().catch(err => {
+          err.should.equal(error);
+        });
+      });
+
     });
 
   });