AssertJ 断言原因消息

Question

有没有办法在使用 AssertJ 时再次抛出异常来检查原因中的消息是否等于某个字符串。

我目前正在做类似的事情：

assertThatThrownBy(() -> SUT.method())
            .isExactlyInstanceOf(IllegalStateException.class)
            .hasRootCauseExactlyInstanceOf(Exception.class);

并且想添加一个断言来检查根本原因中的消息。

Answer 1

不完全是，目前你能做的最好的就是使用hasStackTraceContaining，例如

Throwable runtime = new RuntimeException("no way", 
                                         new Exception("you shall not pass"));

assertThat(runtime).hasCauseInstanceOf(Exception.class)
                   .hasStackTraceContaining("no way")
                   .hasStackTraceContaining("you shall not pass");

Answer 2

自 AssertJ 3.16 以来，有两个新选项可用：

• getCause()：

Throwable runtime = new RuntimeException("no way", 
                                         new Exception("you shall not pass"));

assertThat(runtime).getCause()
                   .hasMessage("you shall not pass");

• getRootCause():

Throwable rootCause = new RuntimeException("go back to the shadow!");
Throwable cause = new Exception("you shall not pass", rootCause);
Throwable runtime = new RuntimeException("no way", cause);

assertThat(runtime).getRootCause()
                   .hasMessage("go back to the shadow!");

---

从 AssertJ 3.14 开始，可以使用 extracting 和 InstanceOfAssertFactory：

Throwable runtime = new RuntimeException("no way", 
                                         new Exception("you shall not pass"));

assertThat(runtime).extracting(Throwable::getCause, as(THROWABLE))
                   .hasMessage("you shall not pass");

as() 是从org.assertj.core.api.Assertions 静态导入的，THROWABLE 是从org.assertj.core.api.InstanceOfAssertFactories 静态导入的。