j-easy#441 test suggested in the issue and a fix

Author: mjureczko

easy-random-core/src/main/java/org/jeasy/random/FieldPopulator.java

@@ -76,7 +76,7 @@ class FieldPopulator {
     }
 
     void populateField(final Object target, final Field field, final RandomizationContext context) throws IllegalAccessException {
-        Randomizer<?> randomizer = getRandomizer(field, context);
+        Randomizer<?> randomizer = getRandomizer(field, context, target.getClass());
         if (randomizer instanceof SkipRandomizer) {
             return;
         }
@@ -113,14 +113,14 @@ void populateField(final Object target, final Field field, final RandomizationCo
         context.popStackItem();
     }
 
-    private Randomizer<?> getRandomizer(Field field, RandomizationContext context) {
+    private Randomizer<?> getRandomizer(Field field, RandomizationContext context, Class<?> fieldTargetType) {
         // issue 241: if there is no custom randomizer by field, then check by type
         Randomizer<?> randomizer = randomizerProvider.getRandomizerByField(field, context);
         if (randomizer == null) {
             Type genericType = field.getGenericType();
             if (isTypeVariable(genericType)) {
                 // if generic type, retrieve actual type from declaring class
-                Class<?> type = getParametrizedType(field, context);
+                Class<?> type = getParametrizedType(field, fieldTargetType);
                 randomizer = randomizerProvider.getRandomizerByType(type, context);
             } else {
                 randomizer = randomizerProvider.getRandomizerByType(field.getType(), context);
@@ -154,18 +154,18 @@ private Object generateRandomValue(final Field field, final RandomizationContext
                 Type genericType = field.getGenericType();
                 if (isTypeVariable(genericType)) {
                     // if generic type, try to retrieve actual type from hierarchy
-                    Class<?> type = getParametrizedType(field, context);
+                    Class<?> type = getParametrizedType(field, context.getTargetType());
                     return easyRandom.doPopulateBean(type, context);
                 }
                 return easyRandom.doPopulateBean(fieldType, context);
             }
         }
     }
 
-    private Class<?> getParametrizedType(Field field, RandomizationContext context) {
+    private Class<?> getParametrizedType(Field field, Class<?> fieldTargetType) {
         Class<?> declaringClass = field.getDeclaringClass();
         TypeVariable<? extends Class<?>>[] typeParameters = declaringClass.getTypeParameters();
-        Type genericSuperclass = getGenericSuperClass(context);
+        Type genericSuperclass = getGenericSuperClass(fieldTargetType);
         ParameterizedType parameterizedGenericSuperType = (ParameterizedType) genericSuperclass;
         Type[] actualTypeArguments = parameterizedGenericSuperType.getActualTypeArguments();
         Type actualTypeArgument = null;
@@ -192,8 +192,7 @@ private Class<?> getParametrizedType(Field field, RandomizationContext context)
     }
 
     // find the generic base class in the hierarchy (which might not be the first super type)
-    private Type getGenericSuperClass(RandomizationContext context) {
-        Class<?> targetType = context.getTargetType();
+    private Type getGenericSuperClass(Class<?> targetType) {
         Type genericSuperclass = targetType.getGenericSuperclass();
         while (targetType != null && !(genericSuperclass instanceof ParameterizedType)) {
             targetType = targetType.getSuperclass();

easy-random-core/src/test/java/org/jeasy/random/Generic2Test.java

@@ -0,0 +1,69 @@
+/*
+ * The MIT License
+ *
+ *   Copyright (c) 2020, Mahmoud Ben Hassine (mahmoud.benhassine@icloud.com)
+ *
+ *   Permission is hereby granted, free of charge, to any person obtaining a copy
+ *   of this software and associated documentation files (the "Software"), to deal
+ *   in the Software without restriction, including without limitation the rights
+ *   to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ *   copies of the Software, and to permit persons to whom the Software is
+ *   furnished to do so, subject to the following conditions:
+ *
+ *   The above copyright notice and this permission notice shall be included in
+ *   all copies or substantial portions of the Software.
+ *
+ *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ *   IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ *   AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ *   LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ *   OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ *   THE SOFTWARE.
+ */
+package org.jeasy.random;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.Serializable;
+import org.junit.jupiter.api.Test;
+
+/** Test suggested in https://github.com/j-easy/easy-random/issues/441 by @seregamorph */
+public class Generic2Test {
+
+    @Test
+    void genericComposedShouldBeCorrectlyPopulated() {
+        // given
+        EasyRandom easyRandom = new EasyRandom();
+
+        // when
+        CompositeResource composite = easyRandom.nextObject(CompositeResource.class);
+
+        // then
+        assertThat(composite.longResource.getId())
+                .isInstanceOf(Long.class)
+                .isNotNull();
+    }
+
+    static abstract class IdResource<K extends Serializable, T extends IdResource<K, ?>> {
+
+        private K id;
+
+        @SuppressWarnings("unchecked")
+        public T setId(K id) {
+            this.id = id;
+            return (T) this;
+        }
+
+        public K getId() {
+            return id;
+        }
+    }
+
+    static class LongResource extends IdResource<Long, LongResource> {
+    }
+
+    static class CompositeResource {
+        private LongResource longResource;
+    }
+}