Introduce ScenarioScoped interface to allow for world reference disposal

Author: Tim te Beek

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

@@ -2,6 +2,7 @@
 
 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;
@@ -138,6 +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();
             }
@@ -148,6 +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/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();
 }

java8/src/main/java/cucumber/runtime/java8/Java8HookDefinition.java

@@ -6,18 +6,19 @@
 import cucumber.api.java8.HookBody;
 import cucumber.api.java8.HookNoArgsBody;
 import cucumber.runtime.HookDefinition;
+import cucumber.runtime.ScenarioScoped;
 import cucumber.runtime.filter.TagPredicate;
 import cucumber.runtime.Timeout;
 import gherkin.pickles.PickleTag;
 
 import java.util.Collection;
 
-public class Java8HookDefinition implements HookDefinition {
+public class Java8HookDefinition implements HookDefinition, ScenarioScoped {
     private final TagPredicate tagPredicate;
     private final int order;
     private final long timeoutMillis;
     private final HookNoArgsBody hookNoArgsBody;
-    private final HookBody hookBody;
+    private HookBody hookBody;
     private final StackTraceElement location;
 
     private Java8HookDefinition(String[] tagExpressions, int order, long timeoutMillis, HookBody hookBody, HookNoArgsBody hookNoArgsBody) {
@@ -69,4 +70,9 @@ public int getOrder() {
     public boolean isScenarioScoped() {
         return true;
     }
+
+    @Override
+    public void disposeScenarioScope() {
+        this.hookBody = null;
+    }
 }

java8/src/main/java/cucumber/runtime/java8/Java8StepDefinition.java

@@ -9,6 +9,7 @@
 import cucumber.api.java8.StepdefBody;
 import io.cucumber.stepexpression.ArgumentMatcher;
 import cucumber.runtime.CucumberException;
+import cucumber.runtime.ScenarioScoped;
 import io.cucumber.stepexpression.ExpressionArgumentMatcher;
 import cucumber.runtime.StepDefinition;
 import io.cucumber.stepexpression.StepExpression;
@@ -24,7 +25,7 @@
 import java.util.List;
 import java.util.Map;
 
-public class Java8StepDefinition implements StepDefinition {
+public class Java8StepDefinition implements StepDefinition, ScenarioScoped {
 
     public static <T extends StepdefBody> Java8StepDefinition create(
         String expression, Class<T> bodyClass, T body, TypeRegistry typeRegistry) {
@@ -37,7 +38,7 @@ public static <T extends StepdefBody> StepDefinition create(
     }
 
     private final long timeoutMillis;
-    private final StepdefBody body;
+    private StepdefBody body;
 
     private final StepExpression expression;
     private final StackTraceElement location;
@@ -161,4 +162,9 @@ private Type requireNonMapOrListType(Type argumentType) {
             return argumentType;
         }
     }
+
+    @Override
+    public void disposeScenarioScope() {
+        this.body = null;
+    }
 }