java - 在 JUnit 5 中，如何在所有测试之前运行代码

Question

注释标记了在类@BeforeAll中的所有测试之前运行的方法。

http://junit.org/junit5/docs/current/user-guide/#writing-tests-annotations

但是有没有办法在所有测试之前在所有类中运行一些代码？

我想确保测试使用一组特定的数据库连接，并且这些连接的全局一次性设置必须在运行任何测试之前发生。

Answer 1

这现在可以通过创建自定义扩展在 JUnit5 中实现，您可以从中在根测试上下文中注册关闭挂钩。

您的扩展程序看起来像这样；

import org.junit.jupiter.api.extension.BeforeAllCallback;
import org.junit.jupiter.api.extension.ExtensionContext;
import static org.junit.jupiter.api.extension.ExtensionContext.Namespace.GLOBAL;

public class YourExtension implements BeforeAllCallback, ExtensionContext.Store.CloseableResource {

    private static boolean started = false;

    @Override
    public void beforeAll(ExtensionContext context) {
        if (!started) {
            started = true;
            // Your "before all tests" startup logic goes here
            // The following line registers a callback hook when the root test context is shut down
            context.getRoot().getStore(GLOBAL).put("any unique name", this);
        }
    }

    @Override
    public void close() {
        // Your "after all tests" logic goes here
    }
}

然后，您需要至少执行一次的任何测试类都可以注释为：

@ExtendWith({YourExtension.class})

当你在多个类上使用这个扩展时，启动和关闭逻辑只会被调用一次。

Answer 2

@Philipp Gayret已经提供的答案在并行测试JUnit （即junit.jupiter.execution.parallel.enabled = true）时存在一些问题。

因此，我将解决方案改编为：

import static org.junit.jupiter.api.extension.ExtensionContext.Namespace.GLOBAL;

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

import org.junit.jupiter.api.extension.BeforeAllCallback;
import org.junit.jupiter.api.extension.ExtensionContext;

public class BeforeAllTestsExtension extends BasicTestClass
        implements BeforeAllCallback, ExtensionContext.Store.CloseableResource {

    private static boolean started = false;
    // Gate keeper to prevent multiple Threads within the same routine
    final static Lock lock = new ReentrantLock();

    @Override
    public void beforeAll(final ExtensionContext context) throws Exception {
        // lock the access so only one Thread has access to it
        lock.lock();
        if (!started) {
            started = true;
            // Your "before all tests" startup logic goes here
            // The following line registers a callback hook when the root test context is
            // shut down
            context.getRoot().getStore(GLOBAL).put("any unique name", this);

            // do your work - which might take some time - 
            // or just uses more time than the simple check of a boolean
        }
        // free the access
        lock.unlock();
    }

    @Override
    public void close() {
        // Your "after all tests" logic goes here
    }
}

如下所述，JUnit5 提供了自动扩展注册。为此，在src/test/resources/名为的目录中/META-INF/services添加一个并添加一个名为org.junit.jupiter.api.extension.Extension. 将您的班级的完全分类名称添加到此文件中，例如

at.myPackage.BeforeAllTestsExtension

接下来在同一个 Junit 配置文件中启用

junit.jupiter.extensions.autodetection.enabled=true

有了这个扩展程序会自动附加到您的所有测试中。

Answer 3

扩展来自@Philipp 的建议，这里有一个更完整的代码片段：

import static org.junit.jupiter.api.extension.ExtensionContext.Namespace.GLOBAL;    
import org.junit.jupiter.api.extension.BeforeAllCallback;
import org.junit.jupiter.api.extension.ExtensionContext;

public abstract class BaseSetupExtension
    implements BeforeAllCallback, ExtensionContext.Store.CloseableResource {

  @Override
  public void beforeAll(ExtensionContext context) throws Exception {
    // We need to use a unique key here, across all usages of this particular extension.
    String uniqueKey = this.getClass().getName();
    Object value = context.getRoot().getStore(GLOBAL).get(uniqueKey);
    if (value == null) {
      // First test container invocation.
      context.getRoot().getStore(GLOBAL).put(uniqueKey, this);
      setup();
    }
  }

  // Callback that is invoked <em>exactly once</em> 
  // before the start of <em>all</em> test containers.
  abstract void setup();

  // Callback that is invoked <em>exactly once</em> 
  // after the end of <em>all</em> test containers.
  // Inherited from {@code CloseableResource}
  public abstract void close() throws Throwable;
}

如何使用：

public class DemoSetupExtension extends BaseSetupExtension {
  @Override
  void setup() {}

  @Override
  public void close() throws Throwable {}
}  

@ExtendWith(DemoSetupExtension.class)
public class TestOne {
   @BeforeAll
   public void beforeAllTestOne { ... }

   @Test
   public void testOne { ... }
}

@ExtendWith(DemoSetupExtension.class)
public class TestTwo {
   @BeforeAll
   public void beforeAllTestTwo { ... }

   @Test
   public void testTwo { ... }
}

测试执行顺序为：

  DemoSetupExtension.setup (*)
  TestOne.beforeAllTestOne
  TestOne.testOne
  TestOne.afterAllTestOne
  TestTwo.beforeAllTestTwo
  TestTwo.testTwo
  TestTwo.afterAllTestTwo
  DemoSetupExtension.close (*)

...无论您选择运行单个@Test（例如TestOne.testOne），还是整个测试类（TestOne），或多个/所有测试，这都是正确的。

Answer 4

您可以使用定义 a 的接口标记每个使用数据库的测试类static BeforeAll（这样它就不能被覆盖）。例如：

interface UsesDatabase {
    @BeforeAll
    static void initializeDatabaseConnections() {
        // initialize database connections
    }
}

该方法将为每个实现类调用一次，因此您需要定义一种方法来仅初始化一次连接，然后对其他调用不执行任何操作。

Answer 5

我不知道这样做的意思。

我会简单地确保 @BeforeAll 的所有代码都调用某个单例以使该 init 工作（可能以一种懒惰的方式避免重复）。

可能不方便......我看到的唯一其他选择：我假设您的测试在特定的 JVM 作业中运行。您可以将代理挂接到该 JVM 运行中，该初始化是否适合您。

除此之外：这两个建议对我来说听起来有点像黑客。在我看来，真正的答案是：退后一步，仔细检查你的环境的依赖关系。然后找到一种方法来准备您的环境，使您的测试出现并且“正确的事情”自动发生。换句话说：考虑调查给你带来这个问题的架构。

Answer 6

以上建议对我不起作用，所以我这样解决了这个问题：

添加到您的 Base 抽象类（我的意思是您在setUpDriver()方法中初始化驱动程序的抽象类）这部分代码：

private static boolean started = false;
static{
    if (!started) {
        started = true;
        try {
            setUpDriver();  //method where you initialize your driver
        } catch (MalformedURLException e) {
        }
    }
}

现在，如果您的测试类将从 Base 抽象类扩展-> setUpDriver()方法将在第一次 @Test 之前执行，每个项目运行一次。

Answer 7

这是我对@Phillip Gayret的非常好的答案的 POC 改进，紧随@Mihnea Giurgea的脚步。

我的子问题：如何访问该共享单例资源？（也许你也想知道这个……）

边栏：在我的实验中，我发现使用多个@ExtendWith(...)似乎可以正确嵌套。即便如此，我记得在我摸索的某个时候它并没有那样工作，所以你应该确保你的用例正常工作[原文如此]。

因为您可能很着急，所以甜点先来：这是运行“文件夹内的所有测试”的输出：

NestedSingleton::beforeAll (setting resource)
Singleton::Start-Once
Base::beforeAll
Colors::blue - resource=Something nice to share!
Colors::gold - resource=Something nice to share!
Base::afterAll
Base::beforeAll
Numbers::one - resource=Something nice to share!
Numbers::tre - resource=Something nice to share!
Numbers::two - resource=Something nice to share!
Base::afterAll
Singleton::Finish-Once
NestedSingleton::close (clearing resource)

当然，只运行一个测试类就可以：

NestedSingleton::beforeAll (setting resource)
Singleton::Start-Once
Base::beforeAll
Numbers::one - resource=Something nice to share!
Numbers::tre - resource=Something nice to share!
Numbers::two - resource=Something nice to share!
Base::afterAll
Singleton::Finish-Once
NestedSingleton::close (clearing resource)

正如现在可以预期的那样，还有一个特定的测试：

NestedSingleton::beforeAll (setting resource)
Singleton::Start-Once
Base::beforeAll
Colors::gold - resource=Something nice to share!
Base::afterAll
Singleton::Finish-Once
NestedSingleton::close (clearing resource)

还在我这儿？然后你可能会喜欢看到实际的代码......

======================================================
junitsingletonresource/Base.java
======================================================
package junitsingletonresource;

import org.junit.jupiter.api.AfterAll;
import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.extension.ExtendWith;

@ExtendWith({Singleton.class})
public abstract class Base extends BaseNestedSingleton
{
    @BeforeAll public static void beforeAll() { System.out.println("Base::beforeAll"); }
    @AfterAll  public static void afterAll () { System.out.println("Base::afterAll" ); }
}

======================================================
junitsingletonresource/Colors.java
======================================================
package junitsingletonresource;

import org.junit.jupiter.api.Test;

public class Colors extends Base
{
    @Test public void blue() { System.out.println("Colors::blue - resource=" + getResource()); }
    @Test public void gold() { System.out.println("Colors::gold - resource=" + getResource()); }
}

======================================================
junitsingletonresource/Numbers.java
======================================================
package junitsingletonresource;

import org.junit.jupiter.api.Test;

public class Numbers extends Base
{
   @Test public void one() { System.out.println("Numbers::one - resource=" + getResource()); }
   @Test public void two() { System.out.println("Numbers::two - resource=" + getResource()); }
   @Test public void tre() { System.out.println("Numbers::tre - resource=" + getResource()); }
}

======================================================
junitsingletonresource/BaseNestedSingleton.java
======================================================
package junitsingletonresource;

import org.junit.jupiter.api.extension.BeforeAllCallback;
import org.junit.jupiter.api.extension.ExtendWith;
import org.junit.jupiter.api.extension.ExtensionContext;

import static org.junit.jupiter.api.extension.ExtensionContext.Namespace.GLOBAL;

/**
 * My riff on Phillip Gayret's solution from: https://stackoverflow.com/a/51556718/5957643
 */
@ExtendWith({BaseNestedSingleton.NestedSingleton.class})
public abstract class BaseNestedSingleton
{
    protected String getResource() { return NestedSingleton.getResource(); }

    static /*pkg*/ class NestedSingleton implements BeforeAllCallback, ExtensionContext.Store.CloseableResource
    {
        private static boolean initialized = false;
        private static String  resource    = "Tests should never see this value (e.g. could be null)";

        private static String getResource() { return resource; }

        @Override
        public void beforeAll(ExtensionContext context)
        {
            if (!initialized) {
                initialized = true;

                // The following line registers a callback hook when the root test context is shut down

                context.getRoot().getStore(GLOBAL).put(this.getClass().getCanonicalName(), this);

                // Your "before all tests" startup logic goes here, e.g. making connections,
                // loading in-memory DB, waiting for external resources to "warm up", etc.

                System.out.println("NestedSingleton::beforeAll (setting resource)");
                resource    = "Something nice to share!";
           }
        }

        @Override
        public void close() {
            if (!initialized) { throw new RuntimeException("Oops - this should never happen"); }

            // Cleanup the resource if needed, e.g. flush files, gracefully end connections, bury any corpses, etc.

            System.out.println("NestedSingleton::close (clearing resource)");
            resource = null;
        }
    }
}

======================================================
junitsingletonresource/Singleton.java
======================================================
package junitsingletonresource;

import org.junit.jupiter.api.extension.BeforeAllCallback;
import org.junit.jupiter.api.extension.ExtensionContext;

import static org.junit.jupiter.api.extension.ExtensionContext.Namespace.GLOBAL;

/**
 * This is pretty much what Phillip Gayret provided, but with some printing for traceability
 */
public class Singleton implements BeforeAllCallback, ExtensionContext.Store.CloseableResource
{
    private static boolean started = false;

    @Override
    public void beforeAll(ExtensionContext context)
    {
        if (!started) {
            started = true;
            System.out.println("Singleton::Start-Once");
            context.getRoot().getStore(GLOBAL).put("any unique name", this);
        }
    }

    @Override
    public void close() { System.out.println("Singleton::Finish-Once"); }
}