do not pass callback when signatures does not match

README.md

@@ -28,29 +28,27 @@ const resolveFive = promback(function () {
     return Promise.resolve(5)
 })
 
-const resolveTen = promback(function () {
-    return 10
-})
-
 timeout(100)
 .then(resolveFive)
 .then(console.log) // logs 5
-.then(resolveTen)
-.then(console.log) // logs 10
 ```
 
 API
 ===
 
 ### `promback (Function fn) -> async Function`
 
-Wraps passed function and returns another one. The prombacked function passes its arguments to wrapped one and returns a promise fulfilled on one of the following cases:
+Wraps passed function and returns prombacked one. The prombacked function passes its arguments to the wrapped one and returns a promise fulfilled on one of the following cases:
 
 - wrapped function called callback added to the arguments,
 - a promise returned by the wrapped function is fulfilled,
 - wrapped function returned a value immediately,
 - wrapped function thrown an error.
 
+If the number of arguments of a prombacked function call does not match to the number of arguments expected by the wrapped function - 1, then callback is not passed to the wrapped function and its returned value resolved directly. This is done so to prevent passing an unexpected argument.
+
+The passed callback signature is the normal node-style callback `(err, value)`.
+
 Prombacked function's `this` reference left not bound to any particular object and is still dynamic.
 
 ### `promback.using (PromiseLib) -> promback`

package.json

@@ -1,6 +1,6 @@
 {
   "name": "promback",
-  "version": "0.1.2",
+  "version": "0.1.3",
   "description": "Level promises/callbacks landscape",
   "main": "promback.js",
   "scripts": {

promback.js

@@ -16,6 +16,10 @@ function using (PromiseLib) {
 
             return new PromiseLib(function (resolve, reject) {
 
+                if (fn.length !== args.length + 1) {
+                    return resolve(fn.apply(that, args))
+                }
+
                 const result = fn.call(that, ... args, function (err, value) {
                     if (err) { reject(err) }
                     resolve(value)

test/promback.spec.js

@@ -150,6 +150,18 @@ function testUsing (contextTitle, promiseLib) {
 
                 assert.strictEqual(result, obj)
             })
+
+            it('does not hang when cb not specified in function',
+                async function () {
+
+                const fn = promback(function () {
+
+                })
+
+                const result = await fn()
+
+                assert.strictEqual(result, undefined)
+            })
         })
     })
 }

test/readme.spec.js

@@ -32,10 +32,8 @@ describe('readme example', function () {
         await timeout(100)
             .then(resolveFive)
             .then(console.log) // logs 5
-            .then(resolveTen)
-            .then(console.log) // logs 10
 
-        assert.deepStrictEqual(output, [ [ 5 ], [ 10 ] ])
+        assert.deepStrictEqual(output, [ [ 5 ] ])
     })
 
     it('uses bluebird promise', function () {