Adding tests for the <Map> component.

src/components/map/Map.tsx

@@ -1,4 +1,4 @@
-import react, { useCallback, useState } from 'react';
+import react, { useCallback } from 'react';
 import { atom, useAtom } from 'jotai';
 
 import Handlers from './Handlers';
@@ -8,12 +8,26 @@ import { Point, TileFactory } from './types';
 
 export interface MapProperties {}
 
-const initialCoordinateSystem = {
+/**
+ * Definition of a coordinate system
+ *
+ * The coordinate system is shifted and zoomed (from the viewport origin)
+ *
+ */
+export interface CoordinateSystem {
+  /** Zoom relative to the origin */
+  zoom: number;
+  /** Origin's shift (in pixels) */
+  shift: Point;
+}
+
+const initialCoordinateSystem: CoordinateSystem = {
   zoom: 1,
   shift: { x: 0, y: 0 },
 };
 
-const coordinateSystemAtom = atom(initialCoordinateSystem);
+/** An atom to store the map coordinates system */
+export const coordinateSystemAtom = atom(initialCoordinateSystem);
 
 /**
  * Description of coordinates system transformation