added check.promise method

README.md

@@ -1,4 +1,4 @@
-# check-more-types v1.4.0
+# check-more-types v1.5.0
 
 > Additional type checks for [check-types.js](https://github.com/philbooth/check-types.js)
 
@@ -90,6 +90,7 @@ for advice and examples.
   * [check.defend in module pattern](#checkdefend-in-module-pattern)
 * [Safe callback execution](#safe-callback-execution)
   * [check.then](#checkthen)
+  * [check.promise](#checkpromise)
 
 
 #### check.defined
@@ -610,6 +611,10 @@ exception. For these cases, there is `check.then`
 
 ----
 
+#### check.promise
+
+Returns true if given object has promise methods (`.then`, etc)
+
 ### Small print
 
 Author: Kensho © 2014

bower.json

@@ -1,7 +1,7 @@
 {
   "name": "check-more-types",
   "main": "check-more-types.js",
-  "version": "1.4.0",
+  "version": "1.5.0",
   "homepage": "https://github.com/kensho/check-more-types",
   "license": "MIT",
   "ignore": [

check-more-types.js

@@ -455,6 +455,25 @@
     };
   }
 
+  var promiseSchema = {
+    then: check.fn
+  };
+
+  // work around reserved keywords checks
+  promiseSchema['catch'] = check.fn;
+  promiseSchema['finally'] = check.fn;
+
+  var hasPromiseApi = schema.bind(null, promiseSchema);
+
+  /**
+    Returns true if argument implements promise api (.then, .catch, .finally)
+    @method promise
+  */
+  function isPromise(p) {
+    return typeof p === 'object' &&
+      hasPromiseApi(p);
+  }
+
   // new predicates to be added to check object. Use object to preserve names
   var predicates = {
     defined: defined,
@@ -482,7 +501,8 @@
     git: git,
     arrayOf: arrayOf,
     badItems: badItems,
-    oneOf: oneOf
+    oneOf: oneOf,
+    promise: isPromise
   };
 
   Object.keys(predicates).forEach(function (name) {

docs/use.md

@@ -514,4 +514,8 @@ exception. For these cases, there is `check.then`
     onlyAddTo10(1, 2); // undefined
     // sum is never called because isSum10 condition is false
 
-----
+----
+
+### check.promise
+
+Returns true if given object has promise methods (`.then`, etc)

package.json

@@ -1,7 +1,7 @@
 {
   "name": "check-more-types",
   "description": "Additional type checks for https://github.com/philbooth/check-types.js",
-  "version": "1.4.0",
+  "version": "1.5.0",
   "author": "Gleb Bahmutov <gleb.bahmutov@gmail.com>",
   "bugs": {
     "url": "https://github.com/kensho/check-more-types/issues"

test/unit-tests.js

@@ -13,6 +13,21 @@ describe('check-more-types', function () {
     la(check.fn(check.lowerCase));
   });
 
+  describe('check/promise', function () {
+    it('checks objects api', function () {
+      var p = {
+        then: function () {},
+        catch: function () {},
+        finally: function () {}
+      };
+      la(check.promise(p));
+      la(!check.promise({}));
+      la(!check.promise('foo'));
+      la(!check.promise());
+    });
+
+  });
+
   describe('check/oneOf', function () {
     it('validates color', function () {
       var colors = ['red', 'green', 'blue'];