@@ -0,0 +1,802 @@
+package com.matao;%0A%0Aimport org.junit.jupiter.api.BeforeEach;%0Aimport org.junit.jupiter.api.Test;%0A%0A/**%0A * Created by matao on 2018-11-28.%0A */%0Apublic class Q01_AssignmentOperatorTest %7B%0A%0A    private Q01_AssignmentOperator.MyString s1;%0A    private Q01_AssignmentOperator.MyString s2;%0A    private Q01_AssignmentOperator.MyString s3;%0A%0A    @BeforeEach%0A    void setUp() %7B%0A        s1 = new Q01_AssignmentOperator.MyString(%22aa%22);%0A        s2 = new Q01_AssignmentOperator.MyString(%22bb%22);%0A        s3 = new Q01_AssignmentOperator.MyString(%22cc%22);%0A    %7D%0A%0A    @Test%0A    void test() %7B%0A        System.out.println(s1);%0A        System.out.println(s2);%0A        System.out.println(s3);%0A%0A        s1.assign(s2).assign(s3);%0A%0A        System.out.println(s1);%0A        System.out.println(s2);%0A        System.out.println(s3);%0A    %7D%0A%7D%0A

add test case for AssignmentOperator