diff --git a/screens/Tetris/__tests__/GridManager.test.js b/screens/Tetris/__tests__/GridManager.test.js
index 43d1f0e..8808754 100644
--- a/screens/Tetris/__tests__/GridManager.test.js
+++ b/screens/Tetris/__tests__/GridManager.test.js
@@ -1,10 +1,19 @@
 import React from 'react';
 import GridManager from "../GridManager";
+import ScoreManager from "../ScoreManager";
+import Piece from "../Piece";
 
 let colors = {
     tetrisBackground: "#000002"
 };
 
+jest.mock("../ScoreManager");
+
+afterAll(() => {
+    jest.restoreAllMocks();
+});
+
+
 test('getEmptyLine', () => {
     let g = new GridManager(2, 2, colors);
     expect(g.getEmptyLine(2)).toStrictEqual([
@@ -32,3 +41,63 @@ test('getEmptyGrid', () => {
     expect(g.getEmptyGrid(2, -1)).toStrictEqual([[], []]);
 });
 
+test('getLinesToClear', () => {
+    let g = new GridManager(2, 2, colors);
+    g.getCurrentGrid()[0][0].isEmpty = false;
+    g.getCurrentGrid()[0][1].isEmpty = false;
+    let coord = [{x: 1, y: 0}];
+    expect(g.getLinesToClear(coord)).toStrictEqual([0]);
+
+    g.getCurrentGrid()[0][0].isEmpty = true;
+    g.getCurrentGrid()[0][1].isEmpty = true;
+    g.getCurrentGrid()[1][0].isEmpty = false;
+    g.getCurrentGrid()[1][1].isEmpty = false;
+    expect(g.getLinesToClear(coord)).toStrictEqual([]);
+    coord = [{x: 1, y: 1}];
+    expect(g.getLinesToClear(coord)).toStrictEqual([1]);
+});
+
+test('clearLines', () => {
+    let g = new GridManager(2, 2, colors);
+    let grid = [
+        [
+            {color: colors.tetrisBackground, isEmpty: true},
+            {color: colors.tetrisBackground, isEmpty: true},
+        ],
+        [
+            {color: '0', isEmpty: true},
+            {color: '0', isEmpty: true},
+        ],
+    ];
+    g.getCurrentGrid()[1][0].color = '0';
+    g.getCurrentGrid()[1][1].color = '0';
+    expect(g.getCurrentGrid()).toStrictEqual(grid);
+    let scoreManager = new ScoreManager();
+    g.clearLines([1], scoreManager);
+    grid = [
+        [
+            {color: colors.tetrisBackground, isEmpty: true},
+            {color: colors.tetrisBackground, isEmpty: true},
+        ],
+        [
+            {color: colors.tetrisBackground, isEmpty: true},
+            {color: colors.tetrisBackground, isEmpty: true},
+        ],
+    ];
+    expect(g.getCurrentGrid()).toStrictEqual(grid);
+});
+
+test('freezeTetromino', () => {
+    let g = new GridManager(2, 2, colors);
+    let spy1 = jest.spyOn(GridManager.prototype, 'getLinesToClear')
+        .mockImplementation(() => {});
+    let spy2 = jest.spyOn(GridManager.prototype, 'clearLines')
+        .mockImplementation(() => {});
+    g.freezeTetromino(new Piece({}), null);
+
+    expect(spy1).toHaveBeenCalled();
+    expect(spy2).toHaveBeenCalled();
+
+    spy1.mockRestore();
+    spy2.mockRestore();
+});