Create event consistency test + test code cleanup

src/test/java/fr/xephi/authme/events/EventsConsistencyTest.java

@@ -0,0 +1,94 @@
+package fr.xephi.authme.events;
+
+import org.apache.commons.lang.reflect.MethodUtils;
+import org.bukkit.event.Event;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+import java.io.File;
+import java.lang.reflect.Method;
+import java.lang.reflect.Modifier;
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.hamcrest.Matchers.equalTo;
+import static org.hamcrest.Matchers.nullValue;
+import static org.junit.Assert.assertThat;
+
+/**
+ * Checks the consistency of the AuthMe event classes.
+ */
+public class EventsConsistencyTest {
+
+    private static final String SRC_FOLDER = "src/main/java/";
+    private static final String EVENTS_FOLDER = SRC_FOLDER + "/fr/xephi/authme/events/";
+    private static List<Class<? extends Event>> classes;
+
+    @BeforeClass
+    public static void scanEventClasses() {
+        File eventsFolder = new File(EVENTS_FOLDER);
+        File[] filesInFolder = eventsFolder.listFiles();
+        if (filesInFolder == null || filesInFolder.length == 0) {
+            throw new IllegalStateException("Could not read folder '" + EVENTS_FOLDER + "'. Is it correct?");
+        }
+
+        classes = new ArrayList<>();
+        for (File file : filesInFolder) {
+            Class<? extends Event> clazz = getEventClassFromFile(file);
+            if (clazz != null) {
+                classes.add(clazz);
+            }
+        }
+        if (classes.isEmpty()) {
+            throw new IllegalStateException("Did not find any AuthMe event classes. Is the folder correct?");
+        }
+    }
+
+    @Test
+    public void shouldExtendFromCustomEvent() {
+        for (Class<?> clazz : classes) {
+            assertThat("Class " + clazz.getSimpleName() + " is subtype of CustomEvent",
+                CustomEvent.class.isAssignableFrom(clazz), equalTo(true));
+        }
+    }
+
+    /**
+     * Bukkit requires a static getHandlerList() method on all event classes, see {@link Event}.
+     * This test checks that such a method is present, and that it is <i>absent</i> if the class
+     * is not instantiable (abstract class).
+     */
+    @Test
+    public void shouldHaveStaticEventHandlerMethod() {
+        for (Class<?> clazz : classes) {
+            Method handlerListMethod = MethodUtils.getAccessibleMethod(clazz, "getHandlerList", new Class<?>[]{});
+            if (canBeInstantiated(clazz)) {
+                assertThat("Class " + clazz.getSimpleName() + " has static method getHandlerList()",
+                    handlerListMethod != null && Modifier.isStatic(handlerListMethod.getModifiers()), equalTo(true));
+            } else {
+                assertThat("Non-instantiable class " + clazz.getSimpleName() + " does not have static getHandlerList()",
+                    handlerListMethod, nullValue());
+            }
+        }
+    }
+
+    private static boolean canBeInstantiated(Class<?> clazz) {
+        return !clazz.isInterface() && !clazz.isEnum() && !Modifier.isAbstract(clazz.getModifiers());
+    }
+
+    private static Class<? extends Event> getEventClassFromFile(File file) {
+        String fileName = file.getPath();
+        String className = fileName
+            .substring(SRC_FOLDER.length(), fileName.length() - ".java".length())
+            .replace(File.separator, ".");
+        try {
+            Class<?> clazz = EventsConsistencyTest.class.getClassLoader().loadClass(className);
+            if (Event.class.isAssignableFrom(clazz)) {
+                return (Class<? extends Event>) clazz;
+            }
+            return null;
+        } catch (ClassNotFoundException e) {
+            throw new IllegalStateException("Could not load class '" + className + "'", e);
+        }
+    }
+
+}