BAEL-907: Code example and tests (#2295)

* BAEL-907: Code example and tests

* Moved files to libraries module

* Moved example to test class

* Moved files. Formatted code. Changed object declaring.

* Code fixes according to comments

libraries/src/test/java/com/baeldung/circularfifoqueue/CircularFifoQueueTest.java

@@ -0,0 +1,159 @@
+package com.baeldung.circularfifoqueue;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.apache.commons.collections4.queue.CircularFifoQueue;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class CircularFifoQueueTest {
+
+    private static final int DEFAULT_SIZE = 32;
+
+    private static final int FIXED_SIZE = 5;
+
+    private static final int COLLECTION_SIZE = 7;
+
+    private static final String TEST_COLOR = "Red";
+
+    private static final String TEST_COLOR_BY_INDEX = "Blue";
+
+    @Test
+    public void whenUsingDefualtConstructor_correctSizeQueue() {
+        CircularFifoQueue<String> bits = new CircularFifoQueue<>();
+
+        Assert.assertEquals(DEFAULT_SIZE, bits.maxSize());
+    }
+
+    @Test
+    public void givenAddElements_whenUsingIntConstructor_correctSizeQueue() {
+        CircularFifoQueue<String> colors = new CircularFifoQueue<>(5);
+        colors.add("Red");
+        colors.add("Blue");
+        colors.add("Green");
+        colors.offer("White");
+        colors.offer("Black");
+
+        Assert.assertEquals(FIXED_SIZE, colors.maxSize());
+    }
+
+    @Test
+    public void whenUsingCollectionConstructor_correctSizeQueue() {
+        List<String> days = new ArrayList<>();
+        days.add("Monday");
+        days.add("Tuesday");
+        days.add("Wednesday");
+        days.add("Thursday");
+        days.add("Friday");
+        days.add("Saturday");
+        days.add("Sunday");
+
+        CircularFifoQueue<String> daysOfWeek = new CircularFifoQueue<>(days);
+
+        Assert.assertEquals(COLLECTION_SIZE, daysOfWeek.maxSize());
+    }
+
+    @Test
+    public void givenAddElements_whenGetElement_correctElement() {
+        CircularFifoQueue<String> colors = new CircularFifoQueue<>(5);
+        colors.add("Red");
+        colors.add("Blue");
+        colors.add("Green");
+        colors.offer("White");
+        colors.offer("Black");
+
+        Assert.assertEquals(TEST_COLOR_BY_INDEX, colors.get(1));
+    }
+
+    @Test
+    public void givenAddElements_whenPollElement_correctElement() {
+        CircularFifoQueue<String> colors = new CircularFifoQueue<>(5);
+        colors.add("Red");
+        colors.add("Blue");
+        colors.add("Green");
+        colors.offer("White");
+        colors.offer("Black");
+
+        Assert.assertEquals(TEST_COLOR, colors.poll());
+    }
+
+    @Test
+    public void givenAddElements_whenPeekQueue_correctElement() {
+        CircularFifoQueue<String> colors = new CircularFifoQueue<>(5);
+        colors.add("Red");
+        colors.add("Blue");
+        colors.add("Green");
+        colors.offer("White");
+        colors.offer("Black");
+
+        Assert.assertEquals(TEST_COLOR, colors.peek());
+    }
+
+    @Test
+    public void givenAddElements_whenElementQueue_correctElement() {
+        CircularFifoQueue<String> colors = new CircularFifoQueue<>(5);
+        colors.add("Red");
+        colors.add("Blue");
+        colors.add("Green");
+        colors.offer("White");
+        colors.offer("Black");
+
+        Assert.assertEquals(TEST_COLOR, colors.element());
+    }
+
+    @Test
+    public void givenAddElements_whenRemoveElement_correctElement() {
+        CircularFifoQueue<String> colors = new CircularFifoQueue<>(5);
+        colors.add("Red");
+        colors.add("Blue");
+        colors.add("Green");
+        colors.offer("White");
+        colors.offer("Black");
+
+        Assert.assertEquals(TEST_COLOR, colors.remove());
+    }
+
+    @Test
+    public void givenFullQueue_whenClearQueue_getIsEmpty() {
+        CircularFifoQueue<String> colors = new CircularFifoQueue<>(5);
+        colors.add("Red");
+        colors.add("Blue");
+        colors.add("Green");
+        colors.offer("White");
+        colors.offer("Black");
+
+        colors.clear();
+
+        Assert.assertEquals(true, colors.isEmpty());
+    }
+
+    @Test
+    public void givenFullQueue_whenCheckFull_getIsFull() {
+        CircularFifoQueue<String> colors = new CircularFifoQueue<>(5);
+        colors.add("Red");
+        colors.add("Blue");
+        colors.add("Green");
+        colors.offer("White");
+        colors.offer("Black");
+
+        Assert.assertEquals(false, colors.isFull());
+    }
+
+    @Test
+    public void givenFullQueue_whenAddMoreElements_getIsAtFullCapacity() {
+        CircularFifoQueue<String> colors = new CircularFifoQueue<>(5);
+        colors.add("Red");
+        colors.add("Blue");
+        colors.add("Green");
+        colors.offer("White");
+        colors.offer("Black");
+
+        colors.add("Orange");
+        colors.add("Violet");
+        colors.add("Pink");
+
+        Assert.assertEquals(true, colors.isAtFullCapacity());
+    }
+
+}