[Core] Add StepDefinedEvent (#1634)

Adds a `StepDefinedEvent` to replace the `StepDefinitionReporter` plugin interface.

## Details

Publish an event from `Glue.addStepDefinition`, as `Runner.reportStepDefinitions` is called before step definition classes are instantiated, which fails to pick up on lambda based steps.

## Motivation and Context

Provide an event to listen for steps being registered, so all steps registrations are available, instead of only the annotation based step definitions.
#1633

core/src/main/java/cucumber/api/StepDefinitionReporter.java

@@ -1,7 +1,12 @@
 package cucumber.api;
 
+import cucumber.api.event.StepDefinedEvent;
 import cucumber.runtime.StepDefinition;
 
+/**
+ * @deprecated in favor of {@link StepDefinedEvent}, as Lambda Step Definitions are not reported through this class.
+ */
+@Deprecated
 public interface StepDefinitionReporter extends Plugin {
     /**
      * Called when a step definition is defined

core/src/main/java/cucumber/api/event/CanonicalEventOrder.java

@@ -31,6 +31,7 @@ private static final class FixedEventOrderComparator implements Comparator<Event
                 TestRunStarted.class,
             TestSourceRead.class,
             SnippetsSuggestedEvent.class,
+            StepDefinedEvent.class,
             TestCaseEvent.class,
             TestRunFinished.class
         );

core/src/main/java/cucumber/api/event/EventPublisher.java

@@ -11,6 +11,7 @@ public interface EventPublisher {
      * <li>{@link TestRunStarted} - the first event sent.
      * <li>{@link TestSourceRead} - sent for each feature file read, contains the feature file source.
      * <li>{@link SnippetsSuggestedEvent} - sent for each step that could not be matched to a step definition, contains the raw snippets for the step.
+     * <li>{@link StepDefinedEvent} - sent for each step definition as it is loaded, contains the StepDefinition
      * <li>{@link TestCaseStarted} - sent before starting the execution of a Test Case(/Pickle/Scenario), contains the Test Case
      * <li>{@link TestStepStarted} - sent before starting the execution of a Test Step, contains the Test Step
      * <li>{@link EmbedEvent} - calling scenario.embed in a hook triggers this event.

core/src/main/java/cucumber/api/event/StepDefinedEvent.java

@@ -0,0 +1,13 @@
+package cucumber.api.event;
+
+import cucumber.runtime.StepDefinition;
+
+public class StepDefinedEvent extends TimeStampedEvent {
+    public final StepDefinition stepDefinition;
+
+    public StepDefinedEvent(Long time, Long timeMillis, StepDefinition stepDefinition) {
+        super(time, timeMillis);
+        this.stepDefinition = stepDefinition;
+    }
+
+}

core/src/main/java/cucumber/runner/Glue.java

@@ -2,9 +2,11 @@
 
 import cucumber.runtime.DuplicateStepDefinitionException;
 import cucumber.runtime.HookDefinition;
+import cucumber.runtime.ScenarioScoped;
 import cucumber.runtime.StepDefinition;
 import io.cucumber.stepexpression.Argument;
 import cucumber.api.StepDefinitionReporter;
+import cucumber.api.event.StepDefinedEvent;
 import gherkin.pickles.PickleStep;
 
 import java.util.ArrayList;
@@ -23,13 +25,20 @@ final class Glue implements cucumber.runtime.Glue {
     final List<HookDefinition> afterHooks = new ArrayList<>();
     final List<HookDefinition> afterStepHooks = new ArrayList<>();
 
+    private final EventBus bus;
+
+    public Glue(EventBus bus) {
+        this.bus = bus;
+    }
+
     @Override
     public void addStepDefinition(StepDefinition stepDefinition) {
         StepDefinition previous = stepDefinitionsByPattern.get(stepDefinition.getPattern());
         if (previous != null) {
             throw new DuplicateStepDefinitionException(previous, stepDefinition);
         }
         stepDefinitionsByPattern.put(stepDefinition.getPattern(), stepDefinition);
+        bus.send(new StepDefinedEvent(bus.getTime(), bus.getTimeMillis(), stepDefinition));
     }
 
     @Override
@@ -130,6 +139,10 @@ private void removeScenarioScopedHooks(List<HookDefinition> beforeHooks) {
         Iterator<HookDefinition> hookIterator = beforeHooks.iterator();
         while (hookIterator.hasNext()) {
             HookDefinition hook = hookIterator.next();
+            if (hook instanceof ScenarioScoped) {
+                ScenarioScoped scenarioScopedHookDefinition = (ScenarioScoped) hook;
+                scenarioScopedHookDefinition.disposeScenarioScope();
+            }
             if (hook.isScenarioScoped()) {
                 hookIterator.remove();
             }
@@ -140,6 +153,10 @@ private void removeScenariosScopedStepDefinitions(Map<String, StepDefinition> st
         Iterator<Map.Entry<String, StepDefinition>> stepDefinitionIterator = stepDefinitions.entrySet().iterator();
         while(stepDefinitionIterator.hasNext()){
             StepDefinition stepDefinition = stepDefinitionIterator.next().getValue();
+            if (stepDefinition instanceof ScenarioScoped) {
+                ScenarioScoped scenarioScopedStepDefinition = (ScenarioScoped) stepDefinition;
+                scenarioScopedStepDefinition.disposeScenarioScope();
+            }
             if(stepDefinition.isScenarioScoped()){
                 stepDefinitionIterator.remove();
             }

core/src/main/java/cucumber/runner/Runner.java

@@ -6,12 +6,12 @@
 import cucumber.runtime.Backend;
 import cucumber.runtime.HookDefinition;
 import cucumber.util.FixJava;
-import io.cucumber.core.logging.Logger;
-import io.cucumber.core.logging.LoggerFactory;
-import io.cucumber.core.options.RunnerOptions;
 import gherkin.events.PickleEvent;
 import gherkin.pickles.PickleStep;
 import gherkin.pickles.PickleTag;
+import io.cucumber.core.logging.Logger;
+import io.cucumber.core.logging.LoggerFactory;
+import io.cucumber.core.options.RunnerOptions;
 
 import java.net.URI;
 import java.util.ArrayList;
@@ -22,13 +22,14 @@ public final class Runner {
 
     private static final Logger log = LoggerFactory.getLogger(Runner.class);
 
-    private final Glue glue = new Glue();
+    private final Glue glue;
     private final EventBus bus;
     private final Collection<? extends Backend> backends;
     private final RunnerOptions runnerOptions;
 
     public Runner(EventBus bus, Collection<? extends Backend> backends, RunnerOptions runnerOptions) {
         this.bus = bus;
+        this.glue = new Glue(bus);
         this.runnerOptions = runnerOptions;
         this.backends = backends;
         List<URI> gluePaths = runnerOptions.getGlue();
@@ -134,5 +135,6 @@ private void disposeBackendWorlds() {
         for (Backend backend : backends) {
             backend.disposeWorld();
         }
+        glue.removeScenarioScopedGlue();
     }
 }

core/src/main/java/cucumber/runtime/HookDefinition.java

@@ -21,7 +21,9 @@ public interface HookDefinition {
     int getOrder();
 
     /**
+     * @deprecated replaced with {@link ScenarioScoped}
      * @return true if this instance is scoped to a single scenario, or false if it can be reused across scenarios.
      */
+    @Deprecated
     boolean isScenarioScoped();
 }

core/src/main/java/cucumber/runtime/ScenarioScoped.java

@@ -0,0 +1,8 @@
+package cucumber.runtime;
+
+public interface ScenarioScoped {
+    /**
+     * Dispose references to Runtime world to allow garbage collection to run.
+     */
+    void disposeScenarioScope();
+}

core/src/main/java/cucumber/runtime/StepDefinition.java

@@ -44,7 +44,9 @@ public interface StepDefinition {
     String getPattern();
 
     /**
+     * @deprecated replaced with {@link ScenarioScoped}
      * @return true if this instance is scoped to a single scenario, or false if it can be reused across scenarios.
      */
+    @Deprecated
     boolean isScenarioScoped();
 }

core/src/test/java/cucumber/runner/GlueTest.java

@@ -41,12 +41,12 @@ public class GlueTest {
 
     @Before
     public void setUp() {
-        glue = new Glue();
+        glue = new Glue(mock(EventBus.class));
     }
 
     @Test
     public void throws_duplicate_error_on_dupe_stepdefs() {
-        Glue glue = new Glue();
+        Glue glue = new Glue(mock(EventBus.class));
 
         StepDefinition a = mock(StepDefinition.class);
         when(a.getPattern()).thenReturn("hello");