Exist assertion on the assert interface

lib/chai/interface/assert.js

@@ -460,6 +460,48 @@ module.exports = function (chai, util) {
     new Assertion(val, msg).not.to.be.NaN;
   };
 
+  /**
+   * ### .exists
+   *
+   * Asserts that the target is neither `null` nor `undefined`.
+   *
+   *     var foo = 'hi';
+   *
+   *     assert.exists(foo, 'foo is neither `null` nor `undefined`');
+   *
+   * @name exists
+   * @param {Mixed} value
+   * @param {String} message
+   * @namespace Assert
+   * @api public
+   */
+
+  assert.exists = function (val, msg) {
+    new Assertion(val, msg).to.exist;
+  };
+
+  /**
+   * ### .notExists
+   *
+   * Asserts that the target is either `null` or `undefined`.
+   *
+   *     var bar = null
+   *       , baz;
+   *
+   *     assert.notExists(bar);
+   *     assert.notExists(baz, 'baz is either null or undefined');
+   *
+   * @name notExists
+   * @param {Mixed} value
+   * @param {String} message
+   * @namespace Assert
+   * @api public
+   */
+
+  assert.notExists = function (val, msg) {
+    new Assertion(val, msg).to.not.exist;
+  };
+
   /**
    * ### .isUndefined(value, [message])
    *

test/assert.js

@@ -344,6 +344,31 @@ describe('assert', function () {
     }, "expected 'hello' not to be NaN");
   });
 
+  it('exists', function() {
+    var meeber = 'awesome';
+    var iDoNotExist;
+       
+    assert.exists(meeber);
+    assert.exists(0);
+    assert.exists(false);
+    assert.exists('');
+
+    err(function (){
+      assert.exists(iDoNotExist);
+    }, "expected undefined to exist");
+  });
+
+  it('notExists', function() {
+    var meeber = 'awesome';
+    var iDoNotExist;
+       
+    assert.notExists(iDoNotExist);
+
+    err(function (){
+      assert.notExists(meeber);
+    }, "expected 'awesome' to not exist");
+  });
+
   it('isUndefined', function() {
     assert.isUndefined(undefined);