fix: corrected duplicate step when using interface for #2757

CHANGELOG.md

@@ -14,6 +14,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - [Core] Fixed `cucumber.publish.enabled=false` ([#2747](https://github.com/cucumber/cucumber-jvm/pull/2747) M.P. Korstanje)
 - [JUnit Platform Engine] Fixed `cucumber.publish.enabled=false` ([#2747](https://github.com/cucumber/cucumber-jvm/pull/2747) M.P. Korstanje)
 
+### Added 
+- [Java] Added support for step definition classes with interfaces ([#2757](https://github.com/cucumber/cucumber-jvm/issues/2757) Julien Kronegg) 
+
 ## [7.12.0] - 2023-04-29
 ### Added
 - [JUnit Platform Engine] Add constant for fixed.max-pool-size property ([#2713](https://github.com/cucumber/cucumber-jvm/pull/2713) M.P. Korstanje)

cucumber-java/src/main/java/io/cucumber/java/JavaBackend.java

@@ -8,6 +8,7 @@
 import io.cucumber.core.resource.ClasspathScanner;
 import io.cucumber.core.resource.ClasspathSupport;
 
+import java.lang.reflect.Modifier;
 import java.net.URI;
 import java.util.Collection;
 import java.util.List;
@@ -39,8 +40,10 @@ public void loadGlue(Glue glue, List<URI> gluePaths) {
                 .flatMap(Collection::stream)
                 .distinct()
                 .forEach(aGlueClass -> scan(aGlueClass, (method, annotation) -> {
-                    container.addClass(method.getDeclaringClass());
-                    glueAdaptor.addDefinition(method, annotation);
+                    if (!Modifier.isVolatile(method.getModifiers())) {
+                        container.addClass(method.getDeclaringClass());
+                        glueAdaptor.addDefinition(method, annotation);
+                    }
                 }));
     }
 

cucumber-java/src/test/java/io/cucumber/java/JavaBackendTest.java

@@ -4,6 +4,7 @@
 import io.cucumber.core.backend.ObjectFactory;
 import io.cucumber.core.backend.StepDefinition;
 import io.cucumber.java.steps.Steps;
+import io.cucumber.java.stepswithinterface.StepsWithInterface;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
@@ -14,7 +15,6 @@
 import org.mockito.junit.jupiter.MockitoExtension;
 
 import java.net.URI;
-import java.util.Arrays;
 import java.util.List;
 
 import static java.lang.Thread.currentThread;
@@ -54,6 +54,13 @@ void finds_step_definitions_by_classpath_url() {
         verify(factory).addClass(Steps.class);
     }
 
+    @Test
+    void finds_step_definitions_by_classpath_url_with_interface() {
+        backend.loadGlue(glue, singletonList(URI.create("classpath:io/cucumber/java/stepswithinterface")));
+        backend.buildWorld();
+        verify(factory).addClass(StepsWithInterface.class);
+    }
+
     @Test
     void finds_step_definitions_once_by_classpath_url() {
         backend.loadGlue(glue,

cucumber-java/src/test/java/io/cucumber/java/stepswithinterface/StepsInterface.java

@@ -0,0 +1,7 @@
+package io.cucumber.java.stepswithinterface;
+
+public interface StepsInterface {
+
+    Number test();
+
+}

cucumber-java/src/test/java/io/cucumber/java/stepswithinterface/StepsWithInterface.java

@@ -0,0 +1,17 @@
+package io.cucumber.java.stepswithinterface;
+
+import io.cucumber.java.en.Given;
+
+/**
+ * Having a class which implements a parent class will lead to duplicate the
+ * methods which return specialized type (here Number for the interface and
+ * Integer for the subclass). The original method has a "volatile" modifier.
+ */
+public class StepsWithInterface implements StepsInterface {
+
+    @Given("test")
+    public Integer test() {
+        return 1;
+    }
+
+}