> For the complete documentation index, see [llms.txt](https://jack80342.gitbook.io/spring-boot/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jack80342.gitbook.io/spring-boot/iv.-spring-boot-features/43.-testing/43.4-test-utilities/43.4.3-outputcapture.md).

# 43.4.3 OutputCapture

`OutputCapture`是JUnit的一个`Rule`，用于捕获`System.out`和`System.err`输出。你可以将`@Rule`注解capture，然后在断言中调用`toString()`。如下所示：

```java
import org.junit.Rule;
import org.junit.Test;
import org.springframework.boot.test.rule.OutputCapture;

import static org.hamcrest.Matchers.*;
import static org.junit.Assert.*;

public class MyTest {

    @Rule
    public OutputCapture capture = new OutputCapture();

    @Test
    public void testName() throws Exception {
        System.out.println("Hello World!");
        assertThat(capture.toString(), containsString("World"));
    }

}
```