Add support for ordering of stories in the JUnit5 engine.

README.md

@@ -34,6 +34,28 @@ public class BasicStory extends JUnit5Story {
 }
 ```
 
+#### Ordering of test classes
+The ordering of classes is not guaranteed by default by the engine.
+If you need to influence order you can supply your own comparator class name in the parameter `jbehave.execution.order.comparator`
+either in system properties or in the JUnit Platform configuration file named `junit-platform.properties`.
+This comparator needs to implement the `Comparator<TestDescriptor>` interface and have a no-args constructor available.
+
+Example configuration:
+```java
+package com.application.comparator;
+
+public class DisplayNameComparator implements Comparator<TestDescriptor> {
+    @Override
+    public int compare(TestDescriptor o1, TestDescriptor o2) {
+        return o1.getDisplayName().compareTo(o2.getDisplayName());
+    }
+}
+```
+junit-platform.properties:
+```properties
+jbehave.execution.order.comparator=com.application.comparator.DisplayNameComparator
+```
+
 ### JUnit 4
 To use JUnit4 runner please add a dependency for `junit` or `junit-vintage-engine` to your project explicitly.
 Very simple java class with runner implementation:

src/main/java/org/jbehavesupport/engine/JBehaveTestEngine.java

@@ -18,6 +18,7 @@
  */
 package org.jbehavesupport.engine;
 
+import lombok.SneakyThrows;
 import org.jbehavesupport.engine.descriptor.JBehaveTestDescriptor;
 import org.jbehavesupport.engine.discovery.JBehaveDiscoverer;
 import org.jbehavesupport.engine.executor.JBehaveExecutor;
@@ -28,13 +29,17 @@
 import org.junit.platform.engine.TestEngine;
 import org.junit.platform.engine.UniqueId;
 
+import java.util.Comparator;
 import java.util.Optional;
+import java.util.stream.Stream;
 
 import static org.junit.platform.engine.TestExecutionResult.successful;
 
 public final class JBehaveTestEngine implements TestEngine  {
 
-	@Override
+    public static final String COMPARATOR_PROPERTY = "jbehave.execution.order.comparator";
+
+    @Override
 	public String getId() {
 		return "jbehave";
 	}
@@ -56,17 +61,29 @@ public TestDescriptor discover(EngineDiscoveryRequest discoveryRequest, UniqueId
 
     @Override
     public void execute(ExecutionRequest request) {
+        Optional<Comparator<TestDescriptor>> sortingComparator = request.getConfigurationParameters()
+            .get(COMPARATOR_PROPERTY, JBehaveTestEngine::getComparatorInstance);
+
         EngineExecutionListener engineExecutionListener = request.getEngineExecutionListener();
         TestDescriptor engineDescriptor = request.getRootTestDescriptor();
         engineExecutionListener.executionStarted(engineDescriptor);
         JBehaveExecutor jBehaveExecutor = new JBehaveExecutor(request);
-        engineDescriptor.getChildren()
+        Stream<? extends JBehaveTestDescriptor> testDescriptorStream = engineDescriptor.getChildren()
             .stream()
             .map(JBehaveTestDescriptor.class::cast)
-            .filter(JBehaveTestDescriptor::isRunnable)
-            .forEach(jBehaveExecutor::execute);
+            .filter(JBehaveTestDescriptor::isRunnable);
+
+        if (sortingComparator.isPresent()) {
+            testDescriptorStream = testDescriptorStream.sorted(sortingComparator.get());
+        }
+        testDescriptorStream.forEach(jBehaveExecutor::execute);
 
         engineExecutionListener.executionFinished(engineDescriptor, successful());
     }
 
+    @SneakyThrows(ReflectiveOperationException.class)
+    private static Comparator<TestDescriptor> getComparatorInstance(String className) {
+        return (Comparator<TestDescriptor>) Class.forName(className).newInstance();
+    }
+
 }

src/test/groovy/org/jbehavesupport/engine/OrderingTest.groovy

@@ -0,0 +1,91 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.jbehavesupport.engine
+
+import org.jbehavesupport.engine.story.AndStepStories
+import org.jbehavesupport.engine.story.BasicStory
+import org.junit.platform.engine.TestDescriptor
+import org.junit.platform.testkit.engine.EngineTestKit
+import spock.lang.Specification
+import spock.lang.Unroll
+import spock.util.environment.RestoreSystemProperties
+
+import static org.junit.platform.engine.discovery.DiscoverySelectors.selectClass
+import static org.junit.platform.testkit.engine.EventConditions.container
+import static org.junit.platform.testkit.engine.EventConditions.engine
+import static org.junit.platform.testkit.engine.EventConditions.event
+import static org.junit.platform.testkit.engine.EventConditions.finishedSuccessfully
+import static org.junit.platform.testkit.engine.EventConditions.started
+import static org.junit.platform.testkit.engine.EventConditions.test
+
+class OrderingTest extends Specification {
+
+    @Unroll
+    @RestoreSystemProperties
+    def "Test ordering with #comparatorClassName"() {
+        given:
+        System.setProperty("jbehave.report.level", "STORY")
+        System.setProperty(JBehaveTestEngine.COMPARATOR_PROPERTY, comparatorClassName)
+        EngineTestKit.Builder builder = EngineTestKit.engine("jbehave")
+            .enableImplicitConfigurationParameters(true)
+            .selectors(selectClass(BasicStory), selectClass(AndStepStories))
+
+        when:
+        def executionResults = builder.execute()
+
+        then:
+        executionResults.allEvents()
+            .assertEventsMatchExactly(
+                event(engine(), started()),
+                event(container(firstClass), started()),
+                event(test(firstStory), started()),
+                event(test(firstStory), finishedSuccessfully()),
+                event(container(firstClass), finishedSuccessfully()),
+                event(container(secondClass), started()),
+                event(test(secondStory), started()),
+                event(test(secondStory), finishedSuccessfully()),
+                event(container(secondClass), finishedSuccessfully()),
+                event(engine(), finishedSuccessfully())
+            )
+
+        where:
+        comparatorClassName                   || firstStory    || firstClass     || secondStory   || secondClass
+        ReverseComparator.class.getName()     || "basic_story" || BasicStory     || "AndStep"     || AndStepStories
+        DisplayNameComparator.class.getName() || "AndStep"     || AndStepStories || "basic_story" || BasicStory
+
+    }
+
+}
+
+class ReverseComparator implements Comparator<TestDescriptor> {
+
+    private DisplayNameComparator displayNameComparator = new DisplayNameComparator()
+
+    @Override
+    int compare(TestDescriptor o1, TestDescriptor o2) {
+        displayNameComparator.reversed().compare(o1, o2)
+    }
+}
+
+class DisplayNameComparator implements Comparator<TestDescriptor> {
+    @Override
+    int compare(TestDescriptor o1, TestDescriptor o2) {
+        o1.displayName <=> o2.displayName
+    }
+}