OutputCapture是一个JUnit Rule，用于捕获System.out和System.err输出。只需简单的将捕获声明为一个@Rule，并使用toString()断言：
import org.junit.Rule;
import org.junit.Test;
import org.springframework.boot.test.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"));
}
}