Use a fake pad to make tests runnable

dungeonbattle/display/display.py

@@ -1,5 +1,7 @@
 import curses
-from typing import Any
+from typing import Any, Union
+
+from dungeonbattle.tests.screen import FakePad
 
 
 class Display:
@@ -10,3 +12,9 @@ class Display:
 
     def refresh(self) -> None:
         raise NotImplementedError
+
+    def newpad(self, height: int, width: int) -> Union[FakePad, Any]:
+        if self.screen:
+            return curses.newpad(height, width)
+        else:
+            return FakePad()