From bf1832da8f6aa187c0dee5b458cceabd1148eeaf Mon Sep 17 00:00:00 2001
From: Johannes Link <business@johanneslink.net>
Date: Sun, 14 Apr 2024 11:18:15 +0200
Subject: [PATCH] Fixed bug 562

---
 TODO.md                                       |  3 --
 .../support/JqwikReflectionSupport.java       |  8 +++--
 .../support/JqwikReflectionSupportTests.java  | 36 +++++++++++++++++++
 3 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/TODO.md b/TODO.md
index 6c2f6605b..66cef7cf2 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,8 +1,5 @@
 # 1.8.5
 
-  - Fix class inheritance bug: https://github.com/jqwik-team/jqwik/issues/562
-
-
 # 1.8.x
     - Replace jsr305 with jspecify
 
diff --git a/engine/src/main/java/net/jqwik/engine/support/JqwikReflectionSupport.java b/engine/src/main/java/net/jqwik/engine/support/JqwikReflectionSupport.java
index cbc767f87..4b1ebd038 100644
--- a/engine/src/main/java/net/jqwik/engine/support/JqwikReflectionSupport.java
+++ b/engine/src/main/java/net/jqwik/engine/support/JqwikReflectionSupport.java
@@ -102,6 +102,10 @@ public static <T> T newInstance(Constructor<T> constructor, Object... args) {
 	 * Find all {@linkplain Method methods} as in ReflectionSupport.findMethods(..) but also use outer classes to look for
 	 * methods.
 	 *
+	 * <p>
+	 *     Duplicate methods (through) inheritance are de-duplicated. The first occurrence of a method is kept.
+	 * </p>
+	 *
 	 * @param clazz         The class in which you start the search
 	 * @param predicate     The condition to check for all candidate methods
 	 * @param traversalMode Traverse hierarchy up or down. Determines the order in resulting list.
@@ -113,11 +117,11 @@ public static List<Method> findMethodsPotentiallyOuter(
 		HierarchyTraversalMode traversalMode
 	) {
 		List<Class<?>> searchClasses = getDeclaringClasses(clazz, traversalMode);
-		List<Method> foundMethods = new ArrayList<>();
+		Set<Method> foundMethods = new LinkedHashSet<>();
 		for (Class<?> searchClass : searchClasses) {
 			foundMethods.addAll(ReflectionSupport.findMethods(searchClass, predicate, traversalMode));
 		}
-		return foundMethods;
+		return new ArrayList<>(foundMethods);
 	}
 
 	/**
diff --git a/engine/src/test/java/net/jqwik/engine/support/JqwikReflectionSupportTests.java b/engine/src/test/java/net/jqwik/engine/support/JqwikReflectionSupportTests.java
index 0969314a6..3410ec219 100644
--- a/engine/src/test/java/net/jqwik/engine/support/JqwikReflectionSupportTests.java
+++ b/engine/src/test/java/net/jqwik/engine/support/JqwikReflectionSupportTests.java
@@ -6,6 +6,8 @@
 import java.util.function.*;
 import java.util.stream.*;
 
+import org.junit.platform.commons.support.*;
+
 import net.jqwik.api.*;
 import net.jqwik.api.constraints.*;
 
@@ -182,6 +184,30 @@ void getFunctionMethod() {
 		assertThat(JqwikReflectionSupport.getFunctionMethod(DataOutput.class)).isNotPresent();
 	}
 
+	@Example
+	void findMethodsPotentiallyOuter() {
+		List<Method> methods = JqwikReflectionSupport.findMethodsPotentiallyOuter(
+			AbstractClass.ConcreteSubclass.class,
+			method -> method.getName().startsWith("method"),
+			HierarchyTraversalMode.BOTTOM_UP
+		);
+		assertThat(methods).hasSize(2);
+
+		List<Method> methodsInSub = JqwikReflectionSupport.findMethodsPotentiallyOuter(
+			AbstractClass.ConcreteSubclass.class,
+			method -> method.getName().startsWith("methodInConcreteSubclass"),
+			HierarchyTraversalMode.BOTTOM_UP
+		);
+		assertThat(methodsInSub).hasSize(1);
+
+		List<Method> methodsInBase = JqwikReflectionSupport.findMethodsPotentiallyOuter(
+			AbstractClass.ConcreteSubclass.class,
+			method -> method.getName().startsWith("methodInAbstractClass"),
+			HierarchyTraversalMode.BOTTOM_UP
+		);
+		assertThat(methodsInBase).hasSize(1);
+	}
+
 	private static class Outer {
 
 		Inner createInner() {
@@ -225,3 +251,13 @@ private static class OuterWithConstructor {
 
 	}
 }
+
+abstract class AbstractClass {
+
+	void methodInAbstractClass() {}
+
+	static class ConcreteSubclass extends AbstractClass {
+
+		void methodInConcreteSubclass() {}
+	}
+}
\ No newline at end of file