Ensure checks based on the constructor property passes for fake Dates (#511)

Author: fatso83

src/fake-timers-src.js

@@ -447,6 +447,10 @@ function withGlobal(_global) {
                 } else {
                     super(...arguments);
                 }
+
+                // ensures identity checks using the constructor prop still works
+                // this should have no other functional effect
+                this.constructor = Date;
             }
 
             static [Symbol.hasInstance](instance) {

test/fake-timers-test.js

@@ -3200,6 +3200,15 @@ describe("FakeTimers", function () {
             assert(date instanceof realDate.constructor);
         });
 
+        // issue #510
+        it("creates Date objects where the constructor prop matches the original", function () {
+            const realDate = new Date();
+            const date = new this.clock.Date();
+
+            assert.equals(date.constructor.name, realDate.constructor.name);
+            assert.equals(date.constructor, realDate.constructor);
+        });
+
         it("creates Date objects representing clock time", function () {
             const date = new this.clock.Date();