Add test cases for indexOf and contains method of ArrayUtils class (#215)

* add a test case for indexOf method of ArrayUtils class

* add a test case for indeOf method

* add test cases for contains method

src/test/java/org/apache/commons/collections4/ArrayUtilsTest.java

@@ -0,0 +1,67 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.commons.collections4;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+
+public class ArrayUtilsTest {
+
+    @Test
+    public void testIndexOf() {
+        final Object[] array = new Object[] { "0", "1", "2", "3", null, "0" };
+        assertEquals(-1, ArrayUtils.indexOf(null, null));
+        assertEquals(-1, ArrayUtils.indexOf(null, "0"));
+        assertEquals(-1, ArrayUtils.indexOf(new Object[0], "0"));
+        assertEquals(0, ArrayUtils.indexOf(array, "0"));
+        assertEquals(1, ArrayUtils.indexOf(array, "1"));
+        assertEquals(2, ArrayUtils.indexOf(array, "2"));
+        assertEquals(3, ArrayUtils.indexOf(array, "3"));
+        assertEquals(4, ArrayUtils.indexOf(array, null));
+        assertEquals(-1, ArrayUtils.indexOf(array, "notInArray"));
+    }
+
+    @Test
+    public void testContains() {
+        final Object[] array = new Object[] { "0", "1", "2", "3", null, "0" };
+        assertFalse(ArrayUtils.contains(null, null));
+        assertFalse(ArrayUtils.contains(null, "1"));
+        assertTrue(ArrayUtils.contains(array, "0"));
+        assertTrue(ArrayUtils.contains(array, "1"));
+        assertTrue(ArrayUtils.contains(array, "2"));
+        assertTrue(ArrayUtils.contains(array, "3"));
+        assertTrue(ArrayUtils.contains(array, null));
+        assertFalse(ArrayUtils.contains(array, "notInArray"));
+    }
+
+    @Test
+    public void testContains_LANG_1261() {
+        class LANG1261ParentObject {
+            @Override
+            public boolean equals(final Object o) {
+                return true;
+            }
+        }
+        class LANG1261ChildObject extends LANG1261ParentObject {
+        }
+        final Object[] array = new LANG1261ChildObject[] { new LANG1261ChildObject() };
+        assertTrue(ArrayUtils.contains(array, new LANG1261ParentObject()));
+    }
+}