feat: added unit test for monotonic queue

Author: yeoshuheng

test/dataStructures/queue/MonotonicQueueTest.java

@@ -0,0 +1,57 @@
+package test.dataStructures.queue;
+
+import org.junit.Assert;
+import org.junit.Test;
+import src.dataStructures.queue.MonotonicQueue;
+public class MonotonicQueueTest {
+    @Test
+    public void testEmpty() {
+        MonotonicQueue<Integer> q = new MonotonicQueue<>();
+        Assert.assertEquals(true, q.isEmpty());
+        Assert.assertEquals(null, q.max());
+        Assert.assertEquals(null, q.pop());
+    }
+
+    @Test
+    public void testMax() {
+        MonotonicQueue<Integer> q = new MonotonicQueue<>();
+        q.push(2);
+        Assert.assertEquals("2", q.max().toString());
+        q.push(7);
+        Assert.assertEquals("7", q.max().toString());
+        q.push(1);
+        Assert.assertEquals("7", q.max().toString());
+        q.push(7);
+        Assert.assertEquals("7", q.max().toString());
+        q.push(5);
+        Assert.assertEquals("7", q.max().toString());
+        q.push(4);
+        Assert.assertEquals("7", q.max().toString());
+        q.push(3);
+        q.push(2);
+        q.push(5);
+        Assert.assertEquals("7", q.max().toString());
+    }
+
+    @Test
+    public void testPop() {
+        MonotonicQueue<Integer> q = new MonotonicQueue<>();
+        q.push(2);
+        q.push(7);
+        q.push(1);
+        q.push(7);
+        q.push(5);
+        q.push(4);
+        q.push(3);
+        q.push(2);
+        q.push(5);
+        q.push(2);
+
+        Assert.assertEquals("7", q.pop().toString());
+        Assert.assertEquals("7", q.pop().toString());
+        Assert.assertEquals("5", q.pop().toString());
+        q.pop();
+        Assert.assertEquals("2", q.pop().toString());
+        Assert.assertEquals(null, q.pop());
+    }
+}