In JUnit 5, how to run code before all tests

This is now possible in JUnit5 by creating a custom Extension, from which you can register a shutdown hook on the root test-context.

Your extension would look like this;

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    }}

Then, any tests classes where you need this executed at least once, can be annotated with:

@ExtendWith({YourExtension.class})

When you use this extension on multiple classes, the startup and shutdown logic will only be invoked once.

The already provided answer from @Philipp Gayret has some problems when testing JUnit in parallel (i.e. junit.jupiter.execution.parallel.enabled = true).

Therefore I adapted the solution to:

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    }}

As mentioned below JUnit5 provides an automatic Extension Registration. To do so add a in src/test/resources/ a directory called /META-INF/services and add a file named org.junit.jupiter.api.extension.Extension. Add into this file the fully classified name of your class, e.g.

at.myPackage.BeforeAllTestsExtension

Next enable in the same Junit config file

junit.jupiter.extensions.autodetection.enabled=true

With this the extension is attached automatically to all of your tests.

Extending on suggestion from @Philipp, here's a more complete code snippet:

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;}

How to use:

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 { ... }}

Test execution order will be:

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

...this will be true regardless if you choose to run a single @Test (e.g.TestOne.testOne), or an entire test class (TestOne), or multiple / all tests.