BAEL-1328 (#3099)

* BAEL-1328 How to Invert an Array in Java

* Removing code from evaluation article.

* BAEL-1328
Adjusting spaces and implement inversion with commons lang3 and guava.

* BAEL-1328 Renaming unit test class; using AssertJ.

core-java/src/test/java/com/baeldung/array/ArrayInverterUnitTest.java

@@ -0,0 +1,49 @@
+package com.baeldung.array;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+
+public class ArrayInverterUnitTest {
+
+    private String[] fruits = { "apples", "tomatoes", "bananas", "guavas", "pineapples", "oranges" };
+
+    @Test
+    public void invertArrayWithForLoop() {
+        ArrayInverter inverter = new ArrayInverter();
+        inverter.invertUsingFor(fruits);
+
+        assertThat(new String[] { "oranges", "pineapples", "guavas", "bananas", "tomatoes", "apples" }).isEqualTo(fruits);
+    }
+
+    @Test
+    public void invertArrayWithCollectionsReverse() {
+        ArrayInverter inverter = new ArrayInverter();
+        inverter.invertUsingCollectionsReverse(fruits);
+
+        assertThat(new String[] { "oranges", "pineapples", "guavas", "bananas", "tomatoes", "apples" }).isEqualTo(fruits);
+    }
+
+    @Test
+    public void invertArrayWithStreams() {
+        ArrayInverter inverter = new ArrayInverter();
+
+        assertThat(new String[] { "oranges", "pineapples", "guavas", "bananas", "tomatoes", "apples" }).isEqualTo(inverter.invertUsingStreams(fruits));
+    }
+
+    @Test
+    public void invertArrayWithCommonsLang() {
+        ArrayInverter inverter = new ArrayInverter();
+        inverter.invertUsingCommonsLang(fruits);
+
+        assertThat(new String[] { "oranges", "pineapples", "guavas", "bananas", "tomatoes", "apples" }).isEqualTo(fruits);
+    }
+
+    @Test
+    public void invertArrayWithGuava() {
+        ArrayInverter inverter = new ArrayInverter();
+
+        assertThat(new String[] { "oranges", "pineapples", "guavas", "bananas", "tomatoes", "apples" }).isEqualTo(inverter.invertUsingGuava(fruits));
+    }
+
+}