diff --git a/src/main/java/com/avaje/ebeaninternal/server/util/ArrayStack.java b/src/main/java/com/avaje/ebeaninternal/server/util/ArrayStack.java
index d819a9464..951282205 100644
--- a/src/main/java/com/avaje/ebeaninternal/server/util/ArrayStack.java
+++ b/src/main/java/com/avaje/ebeaninternal/server/util/ArrayStack.java
@@ -10,80 +10,80 @@ import java.util.EmptyStackException;
  */
 public class ArrayStack<E> {
 
-    private final ArrayList<E> list;
+  private final ArrayList<E> list;
 
-    /**
-     * Creates an empty Stack with an initial size.
-     */
-    public ArrayStack(int size) {
-        this.list = new ArrayList<E>(size);
-    }
+  /**
+   * Creates an empty Stack with an initial size.
+   */
+  public ArrayStack(int size) {
+    this.list = new ArrayList<E>(size);
+  }
 
-    /**
-     * Creates an empty Stack.
-     */
-    public ArrayStack() {
-        this.list = new ArrayList<E>();
-    }
+  /**
+   * Creates an empty Stack.
+   */
+  public ArrayStack() {
+    this.list = new ArrayList<E>();
+  }
 
-    /**
-     * Pushes an item onto the top of this stack. 
-     */
-    public E push(E item) {
-        list.add(item);
-        return item;
-    }
+  /**
+   * Pushes an item onto the top of this stack.
+   */
+  public void push(E item) {
+    list.add(item);
+  }
 
-    /**
-     * Removes the object at the top of this stack and returns that object as
-     * the value of this function.
-     */
-    public E pop() {
-        int len = list.size();
-        E obj = peek();
-        list.remove(len - 1);
-        return obj;
+  /**
+   * Removes the object at the top of this stack and returns that object as
+   * the value of this function.
+   */
+  public E pop() {
+    int len = list.size();
+    if (len == 0) {
+      throw new EmptyStackException();
     }
+    return list.remove(len - 1);
+  }
 
-    protected E peekZero(boolean retNull) {
-        int len = list.size();
-        if (len == 0) {
-            if (retNull) {
-                return null;
-            }
-            throw new EmptyStackException();
-        }
-        return list.get(len - 1);
+  protected E peekZero(boolean retNull) {
+    int len = list.size();
+    if (len == 0) {
+      if (retNull) {
+        return null;
+      }
+      throw new EmptyStackException();
     }
+    return list.get(len - 1);
+  }
 
-    /**
-     * Returns the object at the top of this stack without removing it.
-     */
-    public E peek() {
-        return peekZero(false);
-    }
-    
-    /**
-     * Returns the object at the top of this stack without removing it.
-     * If the stack is empty this returns null.
-     */
-    public E peekWithNull() {
-        return peekZero(true);
-    }
-    
-    /**
-     * Tests if this stack is empty.
-     */
-    public boolean isEmpty() {
-        return list.isEmpty();
-    }
+  /**
+   * Returns the object at the top of this stack without removing it.
+   */
+  public E peek() {
+    return peekZero(false);
+  }
 
-    public int size(){
-        return list.size();
-    }
-    
-    public boolean contains(Object o){
-      //noinspection SuspiciousMethodCalls
-      return list.contains(o);
-    }
+  /**
+   * Returns the object at the top of this stack without removing it.
+   * If the stack is empty this returns null.
+   */
+  public E peekWithNull() {
+    return peekZero(true);
+  }
+
+  /**
+   * Tests if this stack is empty.
+   */
+  public boolean isEmpty() {
+    return list.isEmpty();
+  }
+
+  public int size() {
+    return list.size();
+  }
+
+  public boolean contains(Object o) {
+    //noinspection SuspiciousMethodCalls
+    return list.contains(o);
+  }
 }
diff --git a/src/test/java/com/avaje/ebeaninternal/server/util/ArrayStackTest.java b/src/test/java/com/avaje/ebeaninternal/server/util/ArrayStackTest.java
new file mode 100644
index 000000000..e794b72b2
--- /dev/null
+++ b/src/test/java/com/avaje/ebeaninternal/server/util/ArrayStackTest.java
@@ -0,0 +1,103 @@
+package com.avaje.ebeaninternal.server.util;
+
+import org.junit.Test;
+
+import java.util.EmptyStackException;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+
+public class ArrayStackTest {
+
+  @Test
+  public void testPushPop() throws Exception {
+
+    ArrayStack<String> stack = new ArrayStack<String>();
+    stack.push("1");
+    stack.push("2");
+    stack.push("3");
+
+    assertThat(stack.pop()).isEqualTo("3");
+    assertThat(stack.pop()).isEqualTo("2");
+    assertThat(stack.pop()).isEqualTo("1");
+  }
+
+  @Test
+  public void testPushPop_given_stackInitialSizeExceeded() throws Exception {
+
+    ArrayStack<String> stack = new ArrayStack<String>(2);
+    stack.push("1");
+    stack.push("2");
+    stack.push("3");
+
+    assertThat(stack.pop()).isEqualTo("3");
+    assertThat(stack.pop()).isEqualTo("2");
+    assertThat(stack.pop()).isEqualTo("1");
+  }
+
+  @Test(expected = EmptyStackException.class)
+  public void testPop_given_emptyStack_throws() throws Exception {
+
+    ArrayStack<String> stack = new ArrayStack<String>();
+    stack.pop();
+  }
+
+  @Test(expected = EmptyStackException.class)
+  public void testPeek_given_empty_throws() throws Exception {
+
+    ArrayStack<String> stack = new ArrayStack<String>();
+
+    assertThat(stack.peek());
+  }
+
+  @Test
+  public void testPeek_given_notEmpty() throws Exception {
+
+    ArrayStack<String> stack = new ArrayStack<String>();
+    stack.push("1");
+    assertThat(stack.peek()).isEqualTo("1");
+  }
+
+  @Test
+  public void testPeekWithNull() throws Exception {
+
+    ArrayStack<String> stack = new ArrayStack<String>();
+
+    assertThat(stack.peekWithNull()).isNull();
+
+    stack.push("1");
+    assertThat(stack.peekWithNull()).isEqualTo("1");
+  }
+
+  @Test
+  public void testIsEmpty() throws Exception {
+
+    ArrayStack<String> stack = new ArrayStack<String>();
+    assertThat(stack.isEmpty()).isTrue();
+
+    stack.push("1");
+    assertThat(stack.isEmpty()).isFalse();
+  }
+
+  @Test
+  public void testSize() throws Exception {
+
+    ArrayStack<String> stack = new ArrayStack<String>();
+    assertThat(stack.size()).isEqualTo(0);
+
+    stack.push("1");
+    assertThat(stack.size()).isEqualTo(1);
+    stack.push("w");
+    assertThat(stack.size()).isEqualTo(2);
+  }
+
+  @Test
+  public void testContains() throws Exception {
+
+    ArrayStack<String> stack = new ArrayStack<String>();
+    stack.push("1");
+
+    assertThat(stack.contains("1")).isTrue();
+    assertThat(stack.contains("2")).isFalse();
+  }
+}
\ No newline at end of file