Update: Added Swift Unit Tests

Signed-off-by: Son Nguyen <[email protected]>

Game-2048Tests/Game_2048Tests.swift

@@ -1,35 +1,98 @@
-//
-//  Game_2048Tests.swift
-//  Game-2048Tests
-//
-//  Created by Dav Nguyen on 3/19/24.
-//
-
 import XCTest
+@testable import Game_2048
+
+final class GameViewModelTests: XCTestCase {
 
-final class Game_2048Tests: XCTestCase {
+    var gameViewModel: GameViewModel!
 
     override func setUpWithError() throws {
-        // Put setup code here. This method is called before the invocation of each test method in the class.
+        // Initialize GameViewModel before each test
+        gameViewModel = GameViewModel()
     }
 
     override func tearDownWithError() throws {
-        // Put teardown code here. This method is called after the invocation of each test method in the class.
+        // Clean up after each test
+        gameViewModel = nil
+    }
+
+    func testInitialGridSetup() throws {
+        // Test if grid is initialized correctly
+        let nonZeroTiles = gameViewModel.grid.flatMap { $0 }.filter { $0 != 0 }
+        XCTAssertEqual(nonZeroTiles.count, 2, "Grid should start with exactly 2 non-zero tiles.")
+        XCTAssertTrue(nonZeroTiles.allSatisfy { $0 == 2 || $0 == 4 }, "Initial tiles should be 2 or 4.")
+    }
+
+    func testSwipeLeftMergesCorrectly() throws {
+        // Set a custom grid where merging is expected when swiping left
+        gameViewModel.grid = [
+            [2, 2, 4, 0],
+            [0, 4, 4, 0],
+            [0, 0, 0, 0],
+            [0, 0, 0, 0]
+        ]
+
+        gameViewModel.swipe(direction: .left)
+
+        let expectedGrid = [
+            [4, 4, 0, 0],
+            [8, 0, 0, 0],
+            [0, 0, 0, 0],
+            [0, 0, 0, 0]
+        ]
+
+        XCTAssertEqual(gameViewModel.grid, expectedGrid, "Swiping left should correctly merge tiles.")
+    }
+
+    func testAddNewNumberAfterValidMove() throws {
+        // Set a grid with a valid move, swipe left, and ensure a new number is added
+        gameViewModel.grid = [
+            [2, 2, 0, 0],
+            [0, 0, 0, 0],
+            [0, 0, 0, 0],
+            [0, 0, 0, 0]
+        ]
+
+        let oldGrid = gameViewModel.grid
+        gameViewModel.swipe(direction: .left)
+
+        let nonZeroTilesOld = oldGrid.flatMap { $0 }.filter { $0 != 0 }.count
+        let nonZeroTilesNew = gameViewModel.grid.flatMap { $0 }.filter { $0 != 0 }.count
+
+        XCTAssertGreaterThan(nonZeroTilesNew, nonZeroTilesOld, "A new number should be added after a valid swipe.")
+    }
+
+    func testGameOverDetection() throws {
+        // Set a grid where no moves are left and verify game over
+        gameViewModel.grid = [
+            [2, 4, 2, 4],
+            [4, 2, 4, 2],
+            [2, 4, 2, 4],
+            [4, 2, 4, 2]
+        ]
+
+        XCTAssertTrue(gameViewModel.isGameOver(), "The game should detect a game-over state when no moves are left.")
     }
 
-    func testExample() throws {
-        // This is an example of a functional test case.
-        // Use XCTAssert and related functions to verify your tests produce the correct results.
-        // Any test you write for XCTest can be annotated as throws and async.
-        // Mark your test throws to produce an unexpected failure when your test encounters an uncaught error.
-        // Mark your test async to allow awaiting for asynchronous code to complete. Check the results with assertions afterwards.
+    func testGameWinDetection() throws {
+        // Set a grid with the winning tile 2048 and verify the game detects a win
+        gameViewModel.grid = [
+            [2, 4, 2, 4],
+            [4, 2, 4, 2],
+            [2, 2048, 2, 4],
+            [4, 2, 4, 2]
+        ]
+
+        gameViewModel.updateGameStatus()
+
+        XCTAssertTrue(gameViewModel.hasWon, "The game should detect a win when a 2048 tile appears.")
     }
 
     func testPerformanceExample() throws {
-        // This is an example of a performance test case.
+        // Performance test case example
         measure {
-            // Put the code you want to measure the time of here.
+            for _ in 0..<1000 {
+                gameViewModel.swipe(direction: .left)
+            }
         }
     }
-
 }