another level of testing

src/main/java/com/guowei/lv/Announcer.java

@@ -0,0 +1,66 @@
+package com.guowei.lv;
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
+import java.util.ArrayList;
+import java.util.EventListener;
+import java.util.List;
+
+public class Announcer<T extends EventListener> {
+    private final T proxy;
+    private final List<T> listeners = new ArrayList<T>();
+
+
+    public Announcer(Class<? extends T> listenerType) {
+        proxy = listenerType.cast(Proxy.newProxyInstance(
+                listenerType.getClassLoader(),
+                new Class<?>[]{listenerType},
+                new InvocationHandler() {
+                    public Object invoke(Object aProxy, Method method, Object[] args) throws Throwable {
+                        announce(method, args);
+                        return null;
+                    }
+                }));
+    }
+
+    public void addListener(T listener) {
+        listeners.add(listener);
+    }
+
+    public void removeListener(T listener) {
+        listeners.remove(listener);
+    }
+
+    public T announce() {
+        return proxy;
+    }
+
+    private void announce(Method m, Object[] args) {
+        try {
+            for (T listener : listeners) {
+                m.invoke(listener, args);
+            }
+        }
+        catch (IllegalAccessException e) {
+            throw new IllegalArgumentException("could not invoke listener", e);
+        }
+        catch (InvocationTargetException e) {
+            Throwable cause = e.getCause();
+
+            if (cause instanceof RuntimeException) {
+                throw (RuntimeException)cause;
+            }
+            else if (cause instanceof Error) {
+                throw (Error)cause;
+            }
+            else {
+                throw new UnsupportedOperationException("listener threw exception", cause);
+            }
+        }
+    }
+
+    public static <T extends EventListener> Announcer<T> to(Class<? extends T> listenerType) {
+        return new Announcer<T>(listenerType);
+    }
+}

src/main/java/com/guowei/lv/MainWindow.java

@@ -1,7 +1,11 @@
 package com.guowei.lv;
 
+import org.jivesoftware.smackx.workgroup.agent.UserRequest;
+
 import javax.swing.*;
 import java.awt.*;
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
 
 class MainWindow extends JFrame {
 
@@ -11,6 +15,8 @@ class MainWindow extends JFrame {
     public static final String NEW_ITEM_ID_NAME = "new item id";
     public static final String JOIN_BUTTON_NAME = "join button";
 
+    private final Announcer<UserRequestListener> userRequests = Announcer.to(UserRequestListener.class);
+
 
     MainWindow(SnipersTableModel snipers) {
         super(APPLICATION_TITLE);
@@ -24,19 +30,22 @@ class MainWindow extends JFrame {
     private JPanel makeControls() {
         JPanel controls = new JPanel(new FlowLayout());
         final JTextField itemIdField = new JTextField();
+        itemIdField.setColumns(25);
         itemIdField.setName(NEW_ITEM_ID_NAME);
         controls.add(itemIdField);
 
         JButton joinAuctionButton = new JButton("Join Auction");
         joinAuctionButton.setName(JOIN_BUTTON_NAME);
+        joinAuctionButton.addActionListener(e -> userRequests.announce().joinAuction(itemIdField.getText()));
         controls.add(joinAuctionButton);
+
         return controls;
     }
 
-    private void fillContentPanel(JTable snipersTable, JPanel jPanel) {
+    private void fillContentPanel(JTable snipersTable, JPanel controls) {
         final Container contentPane = getContentPane();
         contentPane.setLayout(new BorderLayout());
-        contentPane.add(jPanel, BorderLayout.NORTH);
+        contentPane.add(controls, BorderLayout.NORTH);
         contentPane.add(new JScrollPane(snipersTable), BorderLayout.CENTER);
     }
 
@@ -45,4 +54,8 @@ private JTable makeSnipersTable(SnipersTableModel snipers) {
         snipersTable.setName(SNIPERS_TABLE_NAME);
         return snipersTable;
     }
+
+    public void addUserRequestListener(UserRequestListener userRequestListener) {
+        userRequests.addListener(userRequestListener);
+    }
 }

src/test/java/com/guowei/lv/MainWindowTest.java

@@ -0,0 +1,22 @@
+package com.guowei.lv;
+
+import com.objogate.wl.swing.probe.ValueMatcherProbe;
+import org.junit.Test;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+
+public class MainWindowTest {
+    private final SnipersTableModel tableModel = new SnipersTableModel();
+    private final MainWindow mainWindow = new MainWindow(tableModel);
+    private final AuctionSniperDriver driver = new AuctionSniperDriver(100);
+
+    @Test
+    public void makesUserRequestWhenJoinButtonClicked() {
+        final ValueMatcherProbe<String> buttonProbe = new ValueMatcherProbe<>(equalTo("item-id"), "join request");
+
+        mainWindow.addUserRequestListener(itemId -> buttonProbe.setReceivedValue(itemId));
+
+        driver.startBiddingFor("item-id");
+        driver.check(buttonProbe);
+    }
+}