Merge pull request #6523 from ZhangShangyu/master

add calculateUsingFactory test case

core-java-8/src/test/java/com/baeldung/reduceIfelse/CalculatorUnitTest.java

@@ -29,4 +29,11 @@ public class CalculatorUnitTest {
         int result = calculator.calculate(new AddCommand(3, 7));
         assertEquals(10, result);
     }
+
+    @Test
+    public void whenCalculateUsingFactory_thenReturnCorrectResult() {
+        Calculator calculator = new Calculator();
+        int result = calculator.calculateUsingFactory(3, 4, "add");
+        assertEquals(7, result);
+    }
 }