Fix ClassCastException in SoftAssertions with custom list assertions

HuitaePark · joel-costigliola · commit 32fae3633dae · 2026-04-06T17:19:04.000+02:00
Changed `containsExactlyInAnyOrderForProxy` signature to accept Collection instead of arrays. This prevents ClassCastException caused by strict array type checking in proxies. Fixes #3797
diff --git a/assertj-core/src/test/java/org/assertj/core/api/SoftAssertions_proxied_AbstractListAssert_Test.java b/assertj-core/src/test/java/org/assertj/core/api/SoftAssertions_proxied_AbstractListAssert_Test.java
@@ -0,0 +1,68 @@
+/*
+ * Copyright 2012-2026 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.assertj.core.api;
+
+import static org.assertj.core.api.BDDAssertions.thenNoException;
+import static org.assertj.core.api.SoftAssertions.assertSoftly;
+import static org.assertj.core.util.Lists.list;
+import static org.assertj.core.util.Lists.newArrayList;
+
+import java.util.List;
+
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests for {@link SoftAssertions}, to verify that proxied custom assertions inheriting from {@link AbstractListAssert} do not throw {@link ClassCastException}.
+ *
+ * @author HuitaePark
+ */
+public class SoftAssertions_proxied_AbstractListAssert_Test {
+
+  @Test
+  void should_not_throw_class_cast_exception_when_calling_methods_with_array_args_on_proxied_custom_assertion() {
+    // GIVEN
+    List<String> actual = list("a", "b");
+    List<String> expected = list("a", "b");
+
+    // WHEN / THEN
+    thenNoException().isThrownBy(() -> {
+      assertSoftly(softly -> softly.proxy(TestListAssert.class, List.class, actual)
+                                   .containsExactlyInAnyOrderElementsOf(expected));
+    });
+  }
+
+  static class TestListAssert extends AbstractListAssert<TestListAssert, List<String>, String, ObjectAssert<String>> {
+
+    public TestListAssert(List<String> actual) {
+      super(actual, TestListAssert.class);
+    }
+
+    @Override
+    protected TestListAssert newAbstractIterableAssert(Iterable<? extends String> iterable) {
+      return new TestListAssert(newArrayList(iterable));
+    }
+
+    @Override
+    protected ObjectAssert<String> toAssert(String value, String description) {
+      return new ObjectAssert<>(value);
+    }
+
+    @Override
+    protected ObjectAssert<String> toAssert(String value) {
+      return new ObjectAssert<>(value);
+    }
+  }
+}
