assertj断言机制记录
据说Junit自带org.junit.Assert断言包功能不够完善，assert
Integer num1 = null;
Integer num2 =30;
// 断言空
assertThat(num1).isNull();
// 断言非空
assertThat(num2).isNotNull();
// 断言相等
assertThat(num2).isEqualTo(30);
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参考：https://blog.csdn.net/u011317250/article/details/53216540