feat: unit test for queue

Author: yeoshuheng

test/dataStructures/queue/queueTest.java

@@ -0,0 +1,49 @@
+package test.dataStructures.queue;
+
+import org.junit.Assert;
+import org.junit.Test;
+import src.dataStructures.queue.Queue;
+
+public class queueTest {
+    @Test
+    public void testEmptyQueue() {
+        Queue<Integer> q = new Queue<>();
+        Assert.assertEquals(0, q.size());
+        Assert.assertEquals(true, q.isEmpty());
+        Assert.assertEquals(null, q.dequeue());
+    }
+    @Test
+    public void testEnqueue() {
+        Queue<Integer> q = new Queue<>();
+        q.enqueue(1);
+        q.enqueue(2);
+        q.enqueue(3);
+        Assert.assertEquals(3, q.size());
+    }
+
+    @Test
+    public void testPeek() {
+        Queue<Integer> q = new Queue<>();
+        q.enqueue(1);
+        Assert.assertEquals("1", q.peek().toString());
+        q.enqueue(2);
+        q.enqueue(3);
+        q.peek();
+        Assert.assertEquals("1", q.peek().toString());
+    }
+
+    @Test
+    public void testDequeue() {
+        Queue<Integer> q = new Queue<>();
+        q.enqueue(1);
+        q.enqueue(2);
+        q.enqueue(3);
+        Assert.assertEquals("1", q.dequeue().toString());
+        Assert.assertEquals(2, q.size());
+        q.dequeue();
+        Assert.assertEquals(1, q.size());
+        Assert.assertEquals("3", q.dequeue().toString());
+        Assert.assertEquals(0, q.size());
+    }
+
+}