xUnit

var optionsQuickOrderDb = new DbContextOptionsBuilder<QuickOrder.Entity.DataContext>().UseInMemoryDatabase(Guid.NewGuid().ToString()).Options;           
QuickOrder.Entity.DataContext mockQuickOrderContext = new QuickOrder.Entity.DataContext(optionsQuickOrderDb);

Guid.NewGuid().ToString()为内存数据库名称，相同名称的数据库可共享数据，有时候会带来便利，但应注意Test方法执行顺序带来的问题。

WordsOnIine.CIient.WebApi.v4.Domain
• Dependencies
AutoMapper
Configs
E nums
Exceptions
Extensions
Helper
I Reposito
C* IProjectLanguageRepository.cs
a c* RedisRepository.cs
a c* Repository.cs
a c* RequestRepository.cs
a c* UnitOfWork.cs
IService
a Messages
Models
Repositories
OrderRepository.cs
ProjectLanguageRepository.cs
RedisRepository.cs
RequestRepository.cs

2. File System

Moq

var fileMock = new Mock();
            //Setup mock file using a memory stream
            var content = "Hello World from a Fake File";
            var fileName = "test.txt";
            using (var ms = new MemoryStream())
            {
                using (var writer = new StreamWriter(ms))
                {
                    writer.Write(content);
                    writer.Flush();
                    ms.Position = 0;
                    fileMock.Setup(_ => .OpenReadStream()).Returns(ms);
                    fileMock.Setup( => .FileName).Returns(fileName);
                    fileMock.Setup( => _.Length).Returns(ms.Length);
                }
            }

System.IO.Abstractions

Nuget: System.IO.Abstractions, System.IO.Abstractions.TestingHelpers

MockFileSystem mockFileSystem = new MockFileSystem();List<KeyValuePair<string,string>> source = new List<KeyValuePair<string, string>>() { new KeyValuePair<string, string>("readme.txt", "Information about this package."), new KeyValuePair<string, string>("test.txt","Hello World from a Fake File.") };
using (var ms = new MemoryStream())
{
    using (ZipOutputStream zipOutputStream = new ZipOutputStream(ms))
    {
        zipOutputStream.SetLevel(1);

foreach (var item in source)
        {
            byte[] byteContent = Encoding.UTF8.GetBytes(item.Value);
            ZipEntry entry = new ZipEntry(item.Key);
            entry.DateTime = DateTime.Now;
            zipOutputStream.PutNextEntry(entry);
            zipOutputStream.Write(byteContent, 0, byteContent.Length);
        }
        zipOutputStream.Finish();
        zipOutputStream.Close();
    }

var mockInputFile = new MockFileData(ms.ToArray());
    mockFileSystem.AddFile(@"C:\temp\test.zip", mockInputFile);
}

ZipHelper.RecursiveDecompress(mockFileSystem, @"C:\temp\test.zip", @"C:\temp", true, true);

MockFileData readmeTxtFile = mockFileSystem.GetFile(@"C:\temp\test\readme.txt");
MockFileData testTxtFile = mockFileSystem.GetFile(@"C:\temp\test\test.txt");

Assert.NotNull(readmeTxtFile);
Assert.NotNull(testTxtFile);

3. Redis & RabbitMQ

var mockRedisRepository = new Mock();
mockRedisRepository.Setup(mock => mock.GetNewEntityId(EntityIdNameSpace.Request, userModel.UserName)).Returns(300001);

4. External Api

5. UserModel

Create a UserModel directly using claims

string userGuid = "07CD07F2-CBE0-DE1E-31F2-39FFCE2B68AF";
string userName = "demo1@qq.com";
string displayName = "demo1 DEV";

var claims = new List()
{
    new Claim("http://schemas.xmlsoap.org/ws/2005/05/identity/claims/nameidentifier", userGuid, "http://www.w3.org/2001/XMLSchema#string", "urn:jonckersauthserver"),
    new Claim("http://schemas.xmlsoap.org/ws/2005/05/identity/claims/name", userName, "http://www.w3.org/2001/XMLSchema#string", "urn:jonckersauthserver"),
    new Claim("displayName", displayName, "http://www.w3.org/2001/XMLSchema#string", "urn:jonckersauthserver"),
    new Claim("companyGuid", Guid.Empty.ToString(), "http://www.w3.org/2001/XMLSchema#string", "urn:jonckersauthserver")
};

ClaimsIdentity claimsIdentity = new ClaimsIdentity(claims, "Service", "http://schemas.xmlsoap.org/ws/2005/05/identity/claims/name", "http://schemas.microsoft.com/ws/2008/06/identity/claims/role");
var claimsPrincipal = new ClaimsPrincipal(claimsIdentity);
UserModel userModel = new UserModel(claimsPrincipal);

6.IConfiguration

Var inMemorySettings = new Dictionary<string, string> {
{"TopLevelKey", "TopLevelValue"},
{"SectionName:SomeKey", "SectionValue"},
//...populate as needed for the test};

IConfiguration configuration = new ConfigurationBuilder()
.AddInMemoryCollection(inMemorySettings)
.Build();

From https://stackoverflow.com/questions/64794219/how-to-mock-iconfiguration-getvalue