add(test)：添加单元测试

backend/IMTest/Service/UserServiceTest.cs

@@ -0,0 +1,182 @@
+using Xunit;
+using Microsoft.EntityFrameworkCore;
+using Moq;
+using AutoMapper;
+using IM_API.Services;
+using IM_API.Models;
+using IM_API.Dtos;
+using IM_API.Exceptions;
+using IM_API.Tools;
+using Microsoft.Extensions.Logging;
+using System;
+using System.Threading.Tasks;
+
+public class UserServiceTests
+{
+    private ImContext CreateDbContext()
+    {
+        var options = new DbContextOptionsBuilder<ImContext>()
+            .UseInMemoryDatabase(Guid.NewGuid().ToString())
+            .Options;
+
+        return new ImContext(options);
+    }
+
+    private IMapper CreateMapper()
+    {
+        var config = new MapperConfiguration(cfg =>
+        {
+            cfg.CreateMap<User, UserInfoDto>();
+            cfg.CreateMap<UpdateUserDto, User>();
+        });
+        return config.CreateMapper();
+    }
+
+    private UserService CreateService(ImContext context)
+    {
+        var loggerMock = new Mock<ILogger<UserService>>();
+        var mapper = CreateMapper();
+        return new UserService(context, loggerMock.Object, mapper);
+    }
+
+    // ========== GetUserInfoAsync ==========
+    [Fact]
+    public async Task GetUserInfoAsync_ShouldReturnUser_WhenExists()
+    {
+        var context = CreateDbContext();
+        context.Users.Add(new User { Id = 1, Username = "Tom", Password = "123456" });
+        await context.SaveChangesAsync();
+
+        var service = CreateService(context);
+        var result = await service.GetUserInfoAsync(1);
+
+        Assert.NotNull(result);
+        Assert.Equal("Tom", result.Username);
+    }
+
+    [Fact]
+    public async Task GetUserInfoAsync_ShouldThrow_WhenNotFound()
+    {
+        var service = CreateService(CreateDbContext());
+
+        await Assert.ThrowsAsync<BaseException>(() =>
+            service.GetUserInfoAsync(999)
+        );
+    }
+
+    // ========== GetUserInfoByUsernameAsync ==========
+    [Fact]
+    public async Task GetUserInfoByUsernameAsync_ShouldReturn_WhenExists()
+    {
+        var context = CreateDbContext();
+        context.Users.Add(new User { Id = 2, Username = "Jerry", Password = "aaa" });
+        await context.SaveChangesAsync();
+
+        var service = CreateService(context);
+        var result = await service.GetUserInfoByUsernameAsync("Jerry");
+
+        Assert.NotNull(result);
+        Assert.Equal(2, result.Id);
+    }
+
+    [Fact]
+    public async Task GetUserInfoByUsernameAsync_ShouldThrow_WhenNotFound()
+    {
+        var service = CreateService(CreateDbContext());
+
+        await Assert.ThrowsAsync<BaseException>(() =>
+            service.GetUserInfoByUsernameAsync("Nobody")
+        );
+    }
+
+    // ========== ResetPasswordAsync ==========
+    [Fact]
+    public async Task ResetPasswordAsync_ShouldReset_WhenCorrectPassword()
+    {
+        var context = CreateDbContext();
+        context.Users.Add(new User { Id = 3, Username = "test", Password = "old" });
+        await context.SaveChangesAsync();
+
+        var service = CreateService(context);
+        var result = await service.ResetPasswordAsync(3, "old", "new");
+
+        Assert.True(result);
+        Assert.Equal("new", context.Users.Find(3).Password);
+    }
+
+    [Fact]
+    public async Task ResetPasswordAsync_ShouldThrow_WhenWrongPassword()
+    {
+        var context = CreateDbContext();
+        context.Users.Add(new User { Id = 4, Username = "test", Password = "oldPwd" });
+        await context.SaveChangesAsync();
+
+        var service = CreateService(context);
+
+        await Assert.ThrowsAsync<BaseException>(() =>
+            service.ResetPasswordAsync(4, "wrong", "new")
+        );
+    }
+
+    [Fact]
+    public async Task ResetPasswordAsync_ShouldThrow_WhenUserNotFound()
+    {
+        var service = CreateService(CreateDbContext());
+
+        await Assert.ThrowsAsync<BaseException>(() =>
+            service.ResetPasswordAsync(123, "anything", "new")
+        );
+    }
+
+    // ========== UpdateOlineStatusAsync ==========
+    [Fact]
+    public async Task UpdateOlineStatusAsync_ShouldUpdateStatus()
+    {
+        var context = CreateDbContext();
+        context.Users.Add(new User { Id = 5, Username = "test", Password = "p", OnlineStatusEnum = UserOnlineStatus.Offline });
+        await context.SaveChangesAsync();
+
+        var service = CreateService(context);
+        var result = await service.UpdateOlineStatusAsync(5, UserOnlineStatus.Online);
+
+        Assert.True(result);
+        Assert.Equal(UserOnlineStatus.Online, context.Users.Find(5).OnlineStatusEnum);
+    }
+
+    [Fact]
+    public async Task UpdateOlineStatusAsync_ShouldThrow_WhenUserNotFound()
+    {
+        var service = CreateService(CreateDbContext());
+
+        await Assert.ThrowsAsync<BaseException>(() =>
+            service.UpdateOlineStatusAsync(999, UserOnlineStatus.Online)
+        );
+    }
+
+    // ========== UpdateUserAsync ==========
+    [Fact]
+    public async Task UpdateUserAsync_ShouldUpdateUserFields()
+    {
+        var context = CreateDbContext();
+        context.Users.Add(new User { Id = 6, Username = "test", Password = "p", NickName = "OldName" });
+        await context.SaveChangesAsync();
+
+        var service = CreateService(context);
+        var dto = new UpdateUserDto { NickName = "NewName" };
+
+        var result = await service.UpdateUserAsync(6, dto);
+
+        Assert.NotNull(result);
+        Assert.Equal("NewName", context.Users.Find(6).NickName);
+    }
+
+    [Fact]
+    public async Task UpdateUserAsync_ShouldThrow_WhenNotFound()
+    {
+        var service = CreateService(CreateDbContext());
+
+        await Assert.ThrowsAsync<BaseException>(() =>
+            service.UpdateUserAsync(123, new UpdateUserDto { NickName = "Test" })
+        );
+    }
+}