@BeforeAll
注释标记一个方法在类中的所有测试之前运行。
http://junit.org/junit5/docs/current/user-guide/#writing-tests-annotations
但是有没有一种方式可以在所有类中的所有测试之前运行一些代码?
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发生在运行任何测试之前。
@BeforeAll
注释标记一个方法在类中的所有测试之前运行。
http://junit.org/junit5/docs/current/user-guide/#writing-tests-annotations
但是有没有一种方式可以在所有类中的所有测试之前运行一些代码?
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发生在运行任何测试之前。
现在在JUnit5中,通过创建自定义扩展(extension)即可实现此操作,您可以在该扩展(extension)上注册一个关机钩子(shutdown hook)来管理根测试上下文(root test-context)。
您的扩展(extension)应该类似于这样:
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,任何需要执行至少一次的测试类可以使用以下注释进行注释:
@ExtendWith({YourExtension.class})
当您在多个类上使用此扩展时,启动和关闭逻辑只会被调用一次。CloseableResource
中的 close
方法没有被调用,但是 AfterAllCallback
中的 afterAll
方法被调用了。 - Emmanuel TouzerygetOrComputeIfAbsent
方法来避免使用静态变量started
,并使其线程安全。 - kan@Philipp Gayret提供的答案在测试JUnit时存在一些问题,特别是在并行测试中(即junit.jupiter.execution.parallel.enabled = true
)。
因此,我对解决方案进行了改进:
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 {
/** Gate keeper to prevent multiple Threads within the same routine */
private static final Lock LOCK = new ReentrantLock();
/** volatile boolean to tell other threads, when unblocked, whether they should try attempt start-up. Alternatively, could use AtomicBoolean. */
private static volatile boolean started = false;
@Override
public void beforeAll(final ExtensionContext context) throws Exception {
// lock the access so only one Thread has access to it
LOCK.lock();
try {
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
}
} finally {
// 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功能。要使用此功能,请在src/test/resources/
中添加一个名为/META-INF/services
的目录,并添加一个名为org.junit.jupiter.api.extension.Extension
的文件。在此文件中添加您的类的完全限定名称,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
使用此方法,扩展功能将自动附加到您的所有测试中。
延续了@Philipp的建议,下面是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;
}
使用方法:
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 { ... }
}
测试执行顺序将是:
DemoSetupExtension.setup (*)
TestOne.beforeAllTestOne
TestOne.testOne
TestOne.afterAllTestOne
TestTwo.beforeAllTestTwo
TestTwo.testTwo
TestTwo.afterAllTestTwo
DemoSetupExtension.close (*)
private static boolean started = false;
static{
if (!started) {
started = true;
try {
setUpDriver(); //method where you initialize your driver
} catch (MalformedURLException e) {
}
}
}
现在,如果你的测试类继承自抽象基类Base -> setUpDriver() 方法将在第一个@Test之前仅执行一次,每个项目运行一次。
我不知道有什么方法可以做到这一点。
我只需要确保所有的 @BeforeAll 代码调用一个特定的单例来使初始化工作正常运行(可能以懒惰的方式避免重复)。
可能不太方便...我唯一看到的另一个选择是:我假设你的测试在特定的 JVM 作业中运行。你可以将一个代理程序agent挂钩到该 JVM 运行中,为你执行那个初始化工作。
除此之外:这两个建议听起来都有点像 hack。在我看来,真正的答案是:退后一步,仔细检查你的环境及其依赖关系。然后找到一种方法,在你的测试启动并且“正确的事情”自动发生的情况下,为你的环境做好准备。换句话说,考虑研究导致你出现这个问题的架构。
这是我对@Phillip Gayret的非常好的答案进行POC改进,跟随@Mihnea Giurgea的脚步。
我的子问题:如何访问共享单例资源?(也许您也在想这个问题...)
侧边栏:在我的实验中,我发现使用多个@ExtendWith(...)
似乎嵌套正确。即便如此,在我摸索的某个时刻,我记得它并不是那样工作的,所以您应该确保您的用例正常工作。
因为您可能很匆忙,甜点先上:这是运行“文件夹内所有测试”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,只运行一个测试类会返回:
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)
还有一个特定的测试,现在可以期望:
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)
还跟上我了吗?那么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://dev59.com/GFgQ5IYBdhLWcg3wIASb#51556718
*/
@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"); }
}