JUnit 测试只有在我运行它们一个一个地通过时才通过。可能穿线不正确

Question

UPD：标记的答案解决了问题，请参阅它对小修复的评论。

首先请原谅我的乱七八糟的代码。这个问题让我抓狂，我尝试了很多东西来确定问题的根源，但都失败了。

我有一个 Spring 启动网络应用程序，它有 FMonitor 服务。它在应用程序运行时工作运行ning 并在某个文件夹中出现扩展名为“.done”的文件时通知我。当我运行应用程序时，它可以完美运行（至少看起来是这样）。

我决定用测试来练习，扔了三个简单的。当我一次运行他们一个人时，他们就成功了。但是，当我运行整个 class 测试时，只有第一个通过，其他两个失败。

我的测试检查 System.out 并将其与所需的输出进行比较。这对我来说是最奇怪的事情。就是这样。

第一次测试通过，FMonitor 的输出与 assertEquals 完全一样。 找到测试 1 找到测试 2 找到测试3

第二次测试失败。由于某种原因，输出奇怪地翻了一番： 找到测试 1 找到测试 1 找到测试 3 找到测试3

然后第三个失败了。现在输出是三倍： 找到测试 找到测试 找到测试

我的猜测是我对线程做了一些完全错误的事情，所以 fm.monitor() 以某种方式捕获了所有事件和类似的东西。我很困惑。我在这里尝试了很多关于如何实现线程的事情，我不太擅长，但它仍然有效。我还认为 monitor() 的 @Async 注释可能会弄乱某些东西，但删除它并没有改变任何东西。请帮忙。

BunchOfTests

import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

import java.io.*;
import java.util.concurrent.Executor;

@RunWith(SpringRunner.class)
@SpringBootTest(classes = FMonitor.class)
public class BunchOfTests {
    private final ByteArrayOutputStream outContent = new ByteArrayOutputStream();
    private Executor executor;

    @Autowired
    FMonitor fm;

    @Test
    public void test1() throws InterruptedException, IOException {
        Runnable task = () -> {
            System.setOut(new PrintStream(outContent));
            fm.monitor();
            System.setOut(System.out);
        };
        executor = (runnable) -> new Thread(runnable).start();
        executor.executeTask(task);
        Thread.sleep(3000);
        File file1 = new File("C:\dir\test1.done");
        File file2 = new File("C:\dir\test2.done");
        File file3 = new File("C:\dir\test3.done");
        file1.createNewFile();
        file2.createNewFile();
        file3.createNewFile();
        Thread.sleep(3000);
        file1.delete();
        file2.delete();
        file3.delete();
        Assert.assertEquals("Found test1\r\n" + "Found test2\r\n" + "Found test3\r\n", outContent);
    }

    @Test
    public void test2() throws InterruptedException, IOException {
        Runnable task = () -> {
            System.setOut(new PrintStream(outContent));
            fm.monitor();
            System.setOut(System.out);
        };
        executor = (runnable) -> new Thread(runnable).start();
        executor.executeTask(task);
        Thread.sleep(3000);
        File file1 = new File("C:\dir\test1.done");
        File file2 = new File("C:\dir\test2.txt");
        File file3 = new File("C:\dir\test3.done");
        file1.createNewFile();
        file2.createNewFile();
        file3.createNewFile();
        Thread.sleep(3000);
        file1.delete();
        file2.delete();
        file3.delete();
        Assert.assertEquals("Found test1\r\n" + "Found test3\r\n", outContent);
    }

    @Test
    public void test3() throws InterruptedException, IOException {
        Runnable task = () -> {
            System.setOut(new PrintStream(outContent));
            fm.monitor();
            System.setOut(System.out);
        };
        executor = (runnable) -> new Thread(runnable).start();
        executor.executeTask(task);
        Thread.sleep(3000);
        File file = new File("C:\dir\test.done");
        file.createNewFile();
        Thread.sleep(3000);
        file.delete();
        Assert.assertEquals("Found test\r\n", outContent);
    }
}

FMonitor

import org.springframework.stereotype.Service;
import org.srpingframework.scheduling.annotation.Async;

import java.io.IOException;
import java.nio.file.*;

@Service
public class FMonitor {

    @Async("fMonitor")
    public void monitor() {
        Path path = Paths.get("C:\dir");
        try {
            WatchService watchService = FileSystems.getDefault.newWatchService();
            path.register(watchService, StandardWatchEventKinds.ENTRY_CREATE);
            WatchKey key;
            while ((key = watchService.take()) != null) {
                for (WatchEvent<?> event: key.pollEvents()) {
                    String filename = event.context().toString();
                    if (filename.endsWith(".done")) {
                        processFile(filename.substring(0, filename.lastIndexOf('.')));
                    }
                }
                key.reset();
            }
        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
        }
    }

    private void processFile(String filename) {
        System.out.println("Found " + filename);
    }
}

配置

import org.srpingframework.context.annotation.Bean;
import org.srpingframework.context.annotation.Configuration;
import org.srpingframework.scheduling.annotation.EnableAsync;

import java.util.concurrent.Executor;
import java.util.concurrent.Executors;

@Configuration
@EnableAsync
public class AConfiguration {
    @Bean(name = "fMonitor")
    public Executor asyncExecutor() { return Executors.newSingleThreadExecutor(); }
}

Answer 1

对于初学者，您应该在完成后完全停止 WatchService。实现一个执行此操作的方法并使用 @PreDestroy.

进行注释

@Service
public class FMonitor {

    private final WatchService watchService = FileSystems.getDefault.newWatchService();


    @Async("fMonitor")
    public void monitor() {
        Path path = Paths.get("C:\dir");
        try {
            path.register(watchService, StandardWatchEventKinds.ENTRY_CREATE);
            WatchKey key;
            while ((key = watchService.take()) != null) {
                for (WatchEvent<?> event: key.pollEvents()) {
                    String filename = event.context().toString();
                    if (filename.endsWith(".done")) {
                        processFile(filename.substring(0, filename.lastIndexOf('.')));
                    }
                }
                key.reset();
            }
        } catch (IOException | InterruptedException e) {
            e.printStackTrace();
        }
    }

    private void processFile(String filename) {
        System.out.println("Found " + filename);
    }

    @PreDestroy
    public void shutdown() {
      try {
        watchService.close();
      } catch (IOException ex) {}
    }
}

接下来不要使用 @SpringBootTest 它不会给您的测试增加任何复杂性和缓慢性。相反，只需自己实例化它并使用适当的执行程序来启动 monitor 方法。

public class BunchOfTests {

    @Rule
    public OutputCaptureRule output = new OutputCaptureRule();
    
    private ExecutorService executor = Executors.newSingleThreadExecutor();

    private final FMonitor fm = new FMonitor();

    @After
    public void cleanUp() throws Exception {
      fm.shutdown();
      executor.shutdown();
      while (!executor.awaitTermination(100, TimeUnit.MICROSECONDS));
    }

    @Test
    public void test1() throws InterruptedException, IOException {
        executor.submit(() -> fm.monitor());

        Thread.sleep(3000);
        File file1 = new File("C:\dir\test1.done");
        File file2 = new File("C:\dir\test2.done");
        File file3 = new File("C:\dir\test3.done");
        file1.createNewFile();
        file2.createNewFile();
        file3.createNewFile();

        Thread.sleep(3000);
        file1.delete();
        file2.delete();
        file3.delete();
        Assert.assertEquals("Found test1\r\n" + "Found test2\r\n" + "Found test3\r\n", output.toString());
    }

    @Test
    public void test2() throws InterruptedException, IOException {
        executor.submit(() -> fm.monitor());

        Thread.sleep(3000);
        File file1 = new File("C:\dir\test1.done");
        File file2 = new File("C:\dir\test2.txt");
        File file3 = new File("C:\dir\test3.done");
        file1.createNewFile();
        file2.createNewFile();
        file3.createNewFile();

        Thread.sleep(3000);
        file1.delete();
        file2.delete();
        file3.delete();
        Assert.assertEquals("Found test1\r\n" + "Found test3\r\n", output.toString());
    }

    @Test
    public void test3() throws InterruptedException, IOException {
        executor.submit(() -> fm.monitor());

        Thread.sleep(3000);

        File file = new File("C:\dir\test.done");
        file.createNewFile();

        Thread.sleep(3000);
        file.delete();
        Assert.assertEquals("Found test\r\n", output.toString());
    }
}

像这样的东西应该或多或少地做你想要的。

JUnit 测试只有在我运行它们一个一个地通过时才通过。可能穿线不正确

JUnit tests pass only when I run them one by one. Probably incorrect threading

java

junit

spring

multithreading

spring-boot

JUnit 测试只有在我 运行 它们一个一个地通过时才通过。可能穿线不正确

JUnit tests pass only when I run them one by one. Probably incorrect threading

java

junit

spring

multithreading

spring-boot

JUnit 测试只有在我运行它们一个一个地通过时才通过。可能穿线不正确