         task.resolve(nil)
         task.continueWith { context in
             continued = true
-        }
-        task.waitUntilCompleted()
+        }.waitUntilCompleted()
         XCTAssertTrue(continued, "continuation closure should run.")
     }
 

        task.continueWith { context in
            XCTAssertTrue(context.isError(), "error should be occured.")
            return nil
        }
        
        task.waitUntilCompleted()
    }
    
    func testErrorValueShouldBePassed() {

                XCTFail("error value shoule be exist.")
            }
            return nil
        }.waitUntilCompleted()
    }
}
