test: test for CollectionUtil

devkit-utils/src/test/java/com/onixbyte/devkit/utils/CollectionUtilTest.java

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+/*
+ * Copyright (C) 2024-2025 OnixByte.
+ *
+ * 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
+ *
+ *     http://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 com.onixbyte.devkit.utils;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.*;
+import java.util.function.Supplier;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class CollectionUtilTest {
+
+    @Test
+    void chunk_NullOriginalCollection_ThrowsException() {
+        IllegalArgumentException ex = assertThrows(IllegalArgumentException.class,
+                () -> CollectionUtil.chunk(null, 3, ArrayList::new));
+        assertEquals("Collection must not be null.", ex.getMessage());
+    }
+
+    @Test
+    void chunk_NegativeMaxSize_ThrowsException() {
+        IllegalArgumentException ex = assertThrows(IllegalArgumentException.class,
+                () -> CollectionUtil.chunk(List.of(1, 2), -1, ArrayList::new));
+        assertEquals("maxSize must greater than 0.", ex.getMessage());
+    }
+
+    @Test
+    void chunk_NullCollectionFactory_ThrowsException() {
+        IllegalArgumentException ex = assertThrows(IllegalArgumentException.class,
+                () -> CollectionUtil.chunk(List.of(1, 2), 2, null));
+        assertEquals("Factory method cannot be null.", ex.getMessage());
+    }
+
+    @Test
+    void chunk_EmptyCollection_ReturnsOneEmptySubCollection() {
+        List<List<Integer>> chunks = CollectionUtil.chunk(Collections.emptyList(), 3, ArrayList::new);
+        assertEquals(1, chunks.size());
+        assertTrue(chunks.get(0).isEmpty());
+    }
+
+    @Test
+    void chunk_CollectionSizeLessThanMaxSize_ReturnsOneSubCollectionWithAllElements() {
+        List<Integer> list = List.of(1, 2);
+        List<List<Integer>> chunks = CollectionUtil.chunk(list, 5, ArrayList::new);
+        assertEquals(1, chunks.size());
+        assertEquals(list, chunks.get(0));
+    }
+
+    @Test
+    void chunk_CollectionSizeEqualMaxSize_ReturnsOneSubCollectionWithAllElements() {
+        List<Integer> list = List.of(1, 2, 3);
+        List<List<Integer>> chunks = CollectionUtil.chunk(list, 3, ArrayList::new);
+        assertEquals(1, chunks.size());
+        assertEquals(list, chunks.get(0));
+    }
+
+    @Test
+    void chunk_CollectionSizeGreaterThanMaxSize_ReturnsMultipleSubCollections() {
+        List<Integer> list = List.of(1, 2, 3, 4, 5, 6, 7);
+        int maxSize = 3;
+        List<List<Integer>> chunks = CollectionUtil.chunk(list, maxSize, ArrayList::new);
+
+        // Expect 3 subcollections: [1,2,3], [4,5,6], [7]
+        assertEquals(3, chunks.size());
+        assertEquals(List.of(1, 2, 3), chunks.get(0));
+        assertEquals(List.of(4, 5, 6), chunks.get(1));
+        assertEquals(List.of(7), chunks.get(2));
+    }
+
+    @Test
+    void chunk_UsesDifferentCollectionTypeAsSubCollections() {
+        LinkedList<Integer> list = new LinkedList<>(List.of(1, 2, 3, 4));
+        Supplier<LinkedList<Integer>> factory = LinkedList::new;
+        List<LinkedList<Integer>> chunks = CollectionUtil.chunk(list, 2, factory);
+        assertEquals(2, chunks.size());
+        assertInstanceOf(LinkedList.class, chunks.get(0));
+        assertInstanceOf(LinkedList.class, chunks.get(1));
+        assertEquals(List.of(1, 2), chunks.get(0));
+        assertEquals(List.of(3, 4), chunks.get(1));
+    }
+
+    @Test
+    void chunk_CollectionWithOneElementAndMaxSizeOne_ReturnsOneSubCollection() {
+        List<String> list = List.of("a");
+        List<List<String>> chunks = CollectionUtil.chunk(list, 1, ArrayList::new);
+        assertEquals(1, chunks.size());
+        assertEquals(list, chunks.get(0));
+    }
+
+    @Test
+    void chunk_MaxSizeZero_ThrowsException() {
+        IllegalArgumentException ex = assertThrows(IllegalArgumentException.class,
+                () -> CollectionUtil.chunk(List.of(1), 0, ArrayList::new));
+        assertEquals("maxSize must greater than 0.", ex.getMessage());
+    }
+}