Merge pull request #19 from logicalparadox/respond-to

Assertion#respondTo

chai.js

@@ -908,6 +908,32 @@ Assertion.prototype.throw = function (constructor) {
   return this;
 };
 
+/**
+ * # .respondTo(method)
+ *
+ * Assert that object/class will respond to a method.
+ *
+ *      expect(Klass).to.respondTo('bar');
+ *      expect(obj).to.respondTo('bar');
+ *
+ * @name respondTo
+ * @param {String} method
+ * @api public
+ */
+
+Assertion.prototype.respondTo = function (method) {
+  var context = ('function' === typeof this.obj)
+    ? this.obj.prototype[method]
+    : this.obj[method];
+
+  this.assert(
+      'function' === typeof context
+    , 'expected ' + this.inspect + ' to respond to ' + inspect(method)
+    , 'expected ' + this.inspect + ' to respond to ' + inspect(method));
+
+  return this;
+};
+
 /*!
  * Aliases.
  */

lib/assertion.js

@@ -855,6 +855,32 @@ Assertion.prototype.throw = function (constructor) {
   return this;
 };
 
+/**
+ * # .respondTo(method)
+ *
+ * Assert that object/class will respond to a method.
+ *
+ *      expect(Klass).to.respondTo('bar');
+ *      expect(obj).to.respondTo('bar');
+ *
+ * @name respondTo
+ * @param {String} method
+ * @api public
+ */
+
+Assertion.prototype.respondTo = function (method) {
+  var context = ('function' === typeof this.obj)
+    ? this.obj.prototype[method]
+    : this.obj[method];
+
+  this.assert(
+      'function' === typeof context
+    , 'expected ' + this.inspect + ' to respond to ' + inspect(method)
+    , 'expected ' + this.inspect + ' to respond to ' + inspect(method));
+
+  return this;
+};
+
 /*!
  * Aliases.
  */

test/expect.js

@@ -427,4 +427,24 @@ suite('expect', function () {
     }, "expected [Function] to throw error matching /hello/ but got \'testing\'");
   });
 
+  test('respondTo', function(){
+    function Foo(){};
+    Foo.prototype.bar = function(){};
+
+    var bar = {};
+    bar.foo = function(){};
+
+    expect(Foo).to.respondTo('bar');
+    expect(Foo).to.not.respondTo('foo');
+
+    expect(bar).to.respondTo('foo');
+
+    err(function(){
+      expect(Foo).to.respondTo('baz');
+    }, "expected [Function: Foo] to respond to \'baz\'");
+
+    err(function(){
+      expect(bar).to.respondTo('baz');
+    }, "expected { foo: [Function] } to respond to \'baz\'");
+  });
 });

test/should.js

@@ -419,4 +419,25 @@ suite('should', function() {
       (badFn).should.throw(/hello/);
     }, "expected [Function] to throw error matching /hello/ but got \'testing\'");
   });
+
+  test('respondTo', function(){
+    function Foo(){};
+    Foo.prototype.bar = function(){};
+
+    var bar = {};
+    bar.foo = function(){};
+
+    Foo.should.respondTo('bar');
+    Foo.should.not.respondTo('foo');
+
+    bar.should.respondTo('foo');
+
+    err(function(){
+      Foo.should.respondTo('baz');
+    }, "expected [Function: Foo] to respond to \'baz\'");
+
+    err(function(){
+      bar.should.respondTo('baz');
+    }, "expected { foo: [Function] } to respond to \'baz\'");
+  });
 });