circular buffer test init

data-structures/src/test/java/com/baeldung/circularbuffer/CircularBufferUnitTest.java

@@ -0,0 +1,44 @@
+package com.baeldung.circularbuffer;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.Test;
+
+public class CircularBufferUnitTest {
+
+    private final String[] shapes = { "Circle", "Triangle", "Rectangle", "Square", "Rhombus", "Trapezoid", "Pentagon", "Pentagram", "Hexagon", "Hexagram" };
+
+    @Test
+    public void givenCircularBuffer_WhenAnElementIsAddedAndRemoved_thenBufferIsEmpty() {
+
+        int capacity = 2;
+        CircularBuffer<String> buffer = new CircularBuffer<>(capacity);
+
+        assertEquals(capacity, buffer.capacity());
+
+        buffer.offer("Rectangle");
+
+        assertEquals(false, buffer.isEmpty());
+        assertEquals(1, buffer.size());
+
+        buffer.poll();
+
+        assertEquals(true, buffer.isEmpty());
+    }
+
+    @Test
+    public void givenCircularBuffer_WhenElementsAreAddedToCapacity_thenBufferIsFull() {
+
+        int capacity = shapes.length;
+        CircularBuffer<String> buffer = new CircularBuffer<>(capacity);
+
+        assertEquals(true, buffer.isEmpty());
+
+        for (String shape : shapes) {
+            buffer.offer(shape);
+        }
+
+        assertEquals(true, buffer.isFull());
+    }
+
+}