Create Wrapper for instances / revise MockUtils

- Add test resources folder
- Create basic test for Messages (todo: add concrete tests)
- Create WrapperMock
- Change UtilsTest (todo: make it work)

src/test/java/fr/xephi/authme/WrapperMock.java

@@ -0,0 +1,54 @@
+package fr.xephi.authme;
+
+import fr.xephi.authme.util.Wrapper;
+import org.bukkit.Server;
+import org.mockito.Mockito;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.logging.Logger;
+
+/**
+ * Class returning mocks for all calls in {@link Wrapper}.
+ * This class keeps track of its mocks and will always return
+ * the same one for each type.
+ */
+public class WrapperMock extends Wrapper {
+
+    private static Map<Class<?>, Object> mocks = new HashMap<>();
+
+    public WrapperMock() {
+        this((AuthMe) getMock(AuthMe.class));
+    }
+
+    public WrapperMock(AuthMe authMe) {
+        super(authMe);
+    }
+
+    @Override
+    public Logger getLogger() {
+        return getMock(Logger.class);
+    }
+
+    @Override
+    public Server getServer() {
+        return getMock(Server.class);
+    }
+
+    @Override
+    public AuthMe getAuthMe() {
+        return getMock(AuthMe.class);
+    }
+
+    @SuppressWarnings("unchecked")
+    private static <T> T getMock(Class<?> clazz) {
+        Object o = mocks.get(clazz);
+        if (o == null) {
+            o = Mockito.mock(clazz);
+            mocks.put(clazz, o);
+        }
+        return (T) o;
+    }
+
+
+}