Merge b5a054f into df3b5ac

lib/assertions.js

@@ -277,13 +277,12 @@ module.exports = expect => {
   );
 
   expect.addAssertion(
-    '<object> [not] to have (enumerable|configurable|writable) property <string>',
+    '<object> to have (enumerable|configurable|writable) property <string>',
     (expect, subject, key) => {
-      const descriptor = expect.alternations[0];
-      expect(
-        Object.getOwnPropertyDescriptor(subject, key)[descriptor],
-        '[not] to be truthy'
-      );
+      const attribute = expect.alternations[0];
+      const descriptor = Object.getOwnPropertyDescriptor(subject, key);
+      expect(descriptor, 'to be defined');
+      expect(descriptor[attribute], 'to be truthy');
       return subject[key];
     }
   );

test/assertions/to-have-property.spec.js

@@ -29,11 +29,8 @@ describe('to have property assertion', () => {
 
     it('asserts validity of property descriptor', () => {
       expect(subject, 'to have enumerable property', 'a');
-      expect(subject, 'not to have enumerable property', 'enumFalse');
       expect(subject, 'to have configurable property', 'a');
-      expect(subject, 'not to have configurable property', 'configFalse');
       expect(subject, 'to have writable property', 'a');
-      expect(subject, 'not to have writable property', 'writableFalse');
     });
 
     it('throws when assertion fails', () => {
@@ -62,6 +59,15 @@ describe('to have property assertion', () => {
           "to have writable property 'writableFalse'"
       );
     });
+
+    // Regression test
+    it('does not break when the object does not have the given property', function() {
+      expect(
+        () => expect({}, 'to have configurable property', 'foo'),
+        'to throw',
+        "expected {} to have configurable property 'foo'"
+      );
+    });
   });
 
   it('throws when the assertion fails', () => {