Return new assertion instead of this for overwriteProperty

chaijs · Sep 14, 2016 · 21df19c · 21df19c
1 parent c9cb468
commit 21df19c
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diff --git a/lib/chai/utils/overwriteProperty.js b/lib/chai/utils/overwriteProperty.js
@@ -4,7 +4,9 @@
  * MIT Licensed
  */
 
+var chai = require('../../chai');
 var flag = require('./flag');
+var transferFlags = require('./transferFlags');
 
 /**
  * ### overwriteProperty (ctx, name, fn)
@@ -58,7 +60,13 @@ module.exports = function (ctx, name, getter) {
         var result = getter(_super).call(this);
         flag(this, 'keep_ssfi', false);
 
-        return result === undefined ? this : result;
+        if (result !== undefined) {
+          return result;
+        }
+
+        var newAssertion = new chai.Assertion();
+        transferFlags(this, newAssertion);
+        return newAssertion;
       }
     , configurable: true
   });

diff --git a/test/utilities.js b/test/utilities.js
@@ -543,6 +543,53 @@ describe('utilities', function () {
         }
       }
     });
+
+    it('should return new assertion with flags copied over', function() {
+      var assertionConstructor;
+
+      chai.use(function (_chai, utils) {
+        assertionConstructor = _chai.Assertion;
+
+        _chai.Assertion.overwriteProperty('and', function (_super) {
+          return function blah () {
+            utils.flag(this, 'mySpecificFlag', 'value1');
+            utils.flag(this, 'ultraSpecificFlag', 'value2');
+            _super.call(this);
+          };
+        });
+
+        _chai.Assertion.addMethod('checkFlags', function() {
+          this.assert(
+              utils.flag(this, 'mySpecificFlag') === 'value1' &&
+              utils.flag(this, 'ultraSpecificFlag') === 'value2'
+            , 'expected assertion to have specific flags'
+            , "this doesn't matter"
+          );
+        });
+      });
+
+      var assertion1 = expect('foo');
+      var assertion2 = assertion1.is.and;
+
+      // Checking if a new assertion was returned
+      expect(assertion1).to.not.be.equal(assertion2);
+
+      // Check if flags were copied
+      assertion2.checkFlags();
+
+      // If it is, calling length on it should return an assertion, not a function
+      expect([1, 2, 3]).to.be.an.and.length.below(1000);
+
+      // Checking if it's really an instance of an Assertion
+      expect(assertion2).to.be.instanceOf(assertionConstructor);
+
+      // Test chaining `.length` after a property to guarantee it is not a function's `length`
+      expect([1, 2, 3]).to.be.a.and.with.length.above(2);
+      expect([1, 2, 3]).to.be.an.instanceOf(Array).and.have.length.below(4);
+
+      expect(expect([1, 2, 3]).be).to.be.an.instanceOf(assertionConstructor);
+      expect(expect([1, 2, 3]).and).to.be.an.instanceOf(assertionConstructor);
+    });
   });
 
   it('getMessage', function () {