From ce444c5e596ebdd6ab52aff645da0945dc2547b1 Mon Sep 17 00:00:00 2001
From: Phan Huy Tran <p.tran@neusta.de>
Date: Wed, 28 May 2025 09:21:03 +0200
Subject: [PATCH] test: coinflip service

---
 .../de/szut/casino/coinflip/CoinflipDto.java  |  3 +
 .../szut/casino/coinflip/CoinflipService.java |  5 +-
 .../java/de/szut/casino/config/AppConfig.java | 15 +++++
 .../casino/coinflip/CoinflipServiceTest.java  | 64 +++++++++++++++++++
 4 files changed, 85 insertions(+), 2 deletions(-)
 create mode 100644 backend/src/main/java/de/szut/casino/config/AppConfig.java
 create mode 100644 backend/src/test/java/de/szut/casino/coinflip/CoinflipServiceTest.java

diff --git a/backend/src/main/java/de/szut/casino/coinflip/CoinflipDto.java b/backend/src/main/java/de/szut/casino/coinflip/CoinflipDto.java
index 8d5a47b..a7f9adb 100644
--- a/backend/src/main/java/de/szut/casino/coinflip/CoinflipDto.java
+++ b/backend/src/main/java/de/szut/casino/coinflip/CoinflipDto.java
@@ -2,13 +2,16 @@ package de.szut.casino.coinflip;
 
 import de.szut.casino.shared.dto.BetDto;
 import jakarta.validation.constraints.NotNull;
+import lombok.AllArgsConstructor;
 import lombok.Getter;
+import lombok.NoArgsConstructor;
 import lombok.Setter;
 
 import java.math.BigDecimal;
 
 @Getter
 @Setter
+@NoArgsConstructor
 public class CoinflipDto extends BetDto {
     @NotNull(message = "chosen side cannot be null")
     private CoinSide coinSide;
diff --git a/backend/src/main/java/de/szut/casino/coinflip/CoinflipService.java b/backend/src/main/java/de/szut/casino/coinflip/CoinflipService.java
index c706ffa..c6c39d7 100644
--- a/backend/src/main/java/de/szut/casino/coinflip/CoinflipService.java
+++ b/backend/src/main/java/de/szut/casino/coinflip/CoinflipService.java
@@ -9,11 +9,12 @@ import java.util.Random;
 
 @Service
 public class CoinflipService {
-    private final Random random = new Random();
+    private final Random random;
     private final BalanceService balanceService;
 
-    public CoinflipService(BalanceService balanceService) {
+    public CoinflipService(BalanceService balanceService, Random random) {
         this.balanceService = balanceService;
+        this.random = random;
     }
 
     public CoinflipResult play(UserEntity user, CoinflipDto coinflipDto) {
diff --git a/backend/src/main/java/de/szut/casino/config/AppConfig.java b/backend/src/main/java/de/szut/casino/config/AppConfig.java
new file mode 100644
index 0000000..9d9c869
--- /dev/null
+++ b/backend/src/main/java/de/szut/casino/config/AppConfig.java
@@ -0,0 +1,15 @@
+package de.szut.casino.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import java.util.Random;
+
+@Configuration
+public class AppConfig {
+
+    @Bean
+    public Random random() {
+        return new Random();
+    }
+}
diff --git a/backend/src/test/java/de/szut/casino/coinflip/CoinflipServiceTest.java b/backend/src/test/java/de/szut/casino/coinflip/CoinflipServiceTest.java
new file mode 100644
index 0000000..2b15ba0
--- /dev/null
+++ b/backend/src/test/java/de/szut/casino/coinflip/CoinflipServiceTest.java
@@ -0,0 +1,64 @@
+package de.szut.casino.coinflip;
+
+import de.szut.casino.shared.service.BalanceService;
+import de.szut.casino.user.UserEntity;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+
+import java.math.BigDecimal;
+import java.util.Random;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.Mockito.*;
+
+class CoinflipServiceTest {
+
+    @Mock
+    private BalanceService balanceService;
+
+    @Mock
+    private Random random;
+
+    @InjectMocks
+    private CoinflipService coinflipService;
+
+    private UserEntity user;
+    private CoinflipDto coinflipDto;
+
+    @BeforeEach
+    void setUp() {
+        MockitoAnnotations.openMocks(this);
+        user = new UserEntity();
+        user.setBalance(BigDecimal.valueOf(100));
+        coinflipDto = new CoinflipDto(BigDecimal.valueOf(10), CoinSide.HEAD);
+    }
+
+    @Test
+    void testPlay_userWins() {
+        when(random.nextBoolean()).thenReturn(true);
+
+        CoinflipResult result = coinflipService.play(user, coinflipDto);
+
+        assertTrue(result.isWin());
+        assertEquals(BigDecimal.valueOf(20), result.getPayout());
+        assertEquals(CoinSide.HEAD, result.getCoinSide());
+        verify(balanceService, times(1)).subtractFunds(user, BigDecimal.valueOf(10));
+        verify(balanceService, times(1)).addFunds(user, BigDecimal.valueOf(20));
+    }
+
+    @Test
+    void testPlay_userLoses() {
+        when(random.nextBoolean()).thenReturn(false);
+
+        CoinflipResult result = coinflipService.play(user, coinflipDto);
+
+        assertFalse(result.isWin());
+        assertEquals(BigDecimal.ZERO, result.getPayout());
+        assertEquals(CoinSide.TAILS, result.getCoinSide());
+        verify(balanceService, times(1)).subtractFunds(user, BigDecimal.valueOf(10));
+        verify(balanceService, never()).addFunds(any(), any());
+    }
+}