diff --git a/src/main/java/net/laffyco/javamatchingengine/engine/OrderBook.java b/src/main/java/net/laffyco/javamatchingengine/engine/OrderBook.java
index f698430..14d9e9a 100644
--- a/src/main/java/net/laffyco/javamatchingengine/engine/OrderBook.java
+++ b/src/main/java/net/laffyco/javamatchingengine/engine/OrderBook.java
@@ -31,16 +31,11 @@ public class OrderBook {
     private double lastSalePrice;
 
     /**
-     * Create an instance of OrderBook.
-     *
-     * @param pBuyOrders
-     * @param pSellOrders
+     * Constructor.
      */
-    public OrderBook(final List<Order> pBuyOrders,
-            final List<Order> pSellOrders) {
-        super();
-        this.buyOrders = pBuyOrders;
-        this.sellOrders = pSellOrders;
+    public OrderBook() {
+        this.buyOrders = new ArrayList<Order>();
+        this.sellOrders = new ArrayList<Order>();
     }
 
     /**
diff --git a/src/test/java/net/laffyco/javamatchingengine/engine/CancelOrderTests.java b/src/test/java/net/laffyco/javamatchingengine/engine/CancelOrderTests.java
index 195d9b4..f36239c 100644
--- a/src/test/java/net/laffyco/javamatchingengine/engine/CancelOrderTests.java
+++ b/src/test/java/net/laffyco/javamatchingengine/engine/CancelOrderTests.java
@@ -2,9 +2,10 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
-import java.util.ArrayList;
+import javax.annotation.Resource;
 
 import org.junit.jupiter.api.Test;
+import org.mockito.InjectMocks;
 
 /**
  * Test the cancel order functionality.
@@ -17,8 +18,9 @@ public class CancelOrderTests extends MatchingEngineTest {
     /**
      * Order book.
      */
-    private final OrderBook orderBook = new OrderBook(new ArrayList<Order>(),
-            new ArrayList<Order>());
+    @InjectMocks
+    @Resource
+    private OrderBook orderBook;
 
     /**
      * Attempt to cancel an order that doesn't exist.
@@ -125,5 +127,4 @@ public void cancelSellOrderSideGiven() {
         assertEquals(this.orderBook.cancelOrder(order.getId(), side), true);
         assertEquals(this.orderBook.getSellOrders().size(), 0);
     }
-
 }
diff --git a/src/test/java/net/laffyco/javamatchingengine/engine/MatchingEngineTest.java b/src/test/java/net/laffyco/javamatchingengine/engine/MatchingEngineTest.java
index a6dfc8e..892bdd3 100644
--- a/src/test/java/net/laffyco/javamatchingengine/engine/MatchingEngineTest.java
+++ b/src/test/java/net/laffyco/javamatchingengine/engine/MatchingEngineTest.java
@@ -1,5 +1,8 @@
 package net.laffyco.javamatchingengine.engine;
 
+import org.junit.jupiter.api.BeforeEach;
+import org.mockito.MockitoAnnotations;
+
 /**
  * Common test functionality.
  *
@@ -8,6 +11,14 @@
  */
 public abstract class MatchingEngineTest {
 
+    /**
+     * Test setup.
+     */
+    @BeforeEach
+    public void setup() {
+        MockitoAnnotations.openMocks(this);
+    }
+
     /**
      * Add an array of orders to the order book.
      *
diff --git a/src/test/java/net/laffyco/javamatchingengine/engine/OrderBookTests.java b/src/test/java/net/laffyco/javamatchingengine/engine/OrderBookTests.java
index 5b4b710..25f89b7 100644
--- a/src/test/java/net/laffyco/javamatchingengine/engine/OrderBookTests.java
+++ b/src/test/java/net/laffyco/javamatchingengine/engine/OrderBookTests.java
@@ -1,12 +1,14 @@
 package net.laffyco.javamatchingengine.engine;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 
-import java.util.ArrayList;
 import java.util.List;
 
-import org.junit.jupiter.api.BeforeEach;
+import javax.annotation.Resource;
+
 import org.junit.jupiter.api.Test;
+import org.mockito.InjectMocks;
 
 /**
  * Order book tests.
@@ -19,22 +21,24 @@ public class OrderBookTests extends MatchingEngineTest {
     /**
      * Array of orders.
      */
-    private final Order[] orders = {new Order(3, 2, Side.BUY),
-            new Order(3, 2, Side.SELL)};
+    private final Order[] orders = { new Order(3, 2, Side.BUY),
+            new Order(3, 2, Side.SELL) };
 
     /**
      * Test OrderBook.
      */
+    @InjectMocks
+    @Resource
     private OrderBook orderBook;
 
-    /**
-     * Test setup.
-     */
-    @BeforeEach
-    public void setUp() {
-        this.orderBook = new OrderBook(new ArrayList<Order>(),
-                new ArrayList<Order>());
-    }
+//    /**
+//     * Test setup.
+//     */
+//    @BeforeEach
+//    public void setUp() {
+//        this.orderBook = new OrderBook(new ArrayList<Order>(),
+//                new ArrayList<Order>());
+//    }
 
     /**
      * Add a buy order, then add a matching sell order.
@@ -130,4 +134,16 @@ public void findOrder() {
         assertEquals(this.orderBook.findOrder(this.orders[0].getId(),
                 this.orders[0].getSide()), this.orders[0]);
     }
+
+    /**
+     * Test that no orders are cancelled when an invalid side is provided.
+     */
+    @Test
+    public void cancelTestInvalidSide() {
+
+        final String orderId = "";
+
+        final boolean result = this.orderBook.cancelOrder(orderId, null);
+        assertFalse(result);
+    }
 }
diff --git a/src/test/java/net/laffyco/javamatchingengine/engine/OrderTests.java b/src/test/java/net/laffyco/javamatchingengine/engine/OrderTests.java
index 16f18dd..5c19379 100644
--- a/src/test/java/net/laffyco/javamatchingengine/engine/OrderTests.java
+++ b/src/test/java/net/laffyco/javamatchingengine/engine/OrderTests.java
@@ -2,6 +2,8 @@
 
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
+import java.util.Date;
+
 import org.junit.jupiter.api.Test;
 
 /**
@@ -10,22 +12,39 @@
  */
 public class OrderTests extends MatchingEngineTest {
 
+    final int amt = 1;
+    final double price = 2;
+    final Side side = Side.BUY;
+
     /**
      * Compare two orders with different prices.
      */
     @Test
     public void comparePrice() {
-        final int amt = 1;
-        final double price1 = 2;
         final double price2 = 3;
-        final Side side = Side.BUY;
 
-        final Order order1 = new Order(amt, price1, side);
-        final Order order2 = new Order(amt, price2, side);
+        final Order order1 = new Order(this.amt, this.price, this.side);
+        final Order order2 = new Order(this.amt, price2, this.side);
 
         // Assert
         assertTrue(order1.compareTo(order2) < 0);
         assertTrue(order2.compareTo(order1) > 0);
     }
 
-}
+    /**
+     * Compare orders with the same price, so therefore time is taken into
+     * account.
+     */
+    @Test
+    public void compareSamePrice() {
+        final String id = "id";
+        final Order order1 = new Order(this.amt, this.price, id, this.side,
+                new Date(1626518162));
+        final Order order2 = new Order(this.amt, this.price, id, this.side,
+                new Date(1626515150));
+
+        // Assert
+        assertTrue(order1.compareTo(order2) > 0);
+        assertTrue(order2.compareTo(order1) < 0);
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/net/laffyco/javamatchingengine/engine/SpreadTests.java b/src/test/java/net/laffyco/javamatchingengine/engine/SpreadTests.java
index 44dd3ae..1676a66 100644
--- a/src/test/java/net/laffyco/javamatchingengine/engine/SpreadTests.java
+++ b/src/test/java/net/laffyco/javamatchingengine/engine/SpreadTests.java
@@ -2,10 +2,12 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
-import java.util.ArrayList;
 import java.util.Date;
 
+import javax.annotation.Resource;
+
 import org.junit.jupiter.api.Test;
+import org.mockito.InjectMocks;
 
 /**
  * Test the getSpread() functionality.
@@ -17,8 +19,9 @@ public class SpreadTests extends MatchingEngineTest {
     /**
      * Order book.
      */
-    private final OrderBook orderBook = new OrderBook(new ArrayList<Order>(),
-            new ArrayList<Order>());
+    @InjectMocks
+    @Resource
+    private OrderBook orderBook;
 
     @Test
     void spreadTwoOrders() {