Add test.

subprojects/java21/src/test/java/org/mockito/java21/RecordTest.java

@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2023 Mockito contributors
+ * This program is made available under the terms of the MIT License.
+ */
+package org.mockito.java21;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.spy;
+
+import java.util.List;
+
+import org.junit.Test;
+
+public class RecordTest {
+
+    @Test
+    public void given_list_is_already_spied__when_spying_record__then_record_fields_are_correctly_populated() {
+        var ignored = spy(List.of());
+
+        record MyRecord(String name) {
+        }
+        MyRecord spiedRecord = spy(new MyRecord("something"));
+
+        assertThat(spiedRecord.name()).isEqualTo("something");
+    }
+}