使用 MsTest 在 C# 中模拟 SqlConnection、SqlCommand 和 SqlReader

Question

我遇到了这个 and I'm interested in implementing the second answer using Fake. Here's 。

我并没有真正理解那里的所有概念，我仍在阅读和理解 documentation，有人可以帮助使用我的代码吗，我正在尝试访问客户列表以了解如何使用Fake/Shim/Stub/Mock在吗？

您也可以重写 FindAll 方法，以防万一它被重构为接受依赖项。

讨论后编辑

public class Data
{
    private Func<IDbConnection> Factory { get; }

    public Data(Func<IDbConnection> factory)
    {
        Factory = factory;
    }

    public IList<Customer> FindAll()
    {
        using (var connection = Factory.Invoke())
        {
            const string sql = "SELECT Id, Name FROM Customer";
            using (var command = new SqlCommand(sql, (SqlConnection) connection))
            {
                command.Connection.Open();
                using (var reader = command.ExecuteReader())
                {
                    IList<Customer> rows = new List<Customer>();
                    while (reader.Read())
                    {
                        rows.Add(new Customer
                        {
                            Id = reader.GetInt32(reader.GetOrdinal("Id")),
                            Name = reader.GetString(reader.GetOrdinal("Name"))
                        });
                    }
                    return rows;
                }
            }
        }
    }
}

客户

public class Customer
{
    public int Id { get; set; }
    public string Name { get; set; }
}

单元测试

[TestMethod]
public void TestDB()
{
    var commandMock = new Mock<IDbCommand>();

    var readerMock = new Mock<IDataReader>();
    commandMock.Setup(m => m.ExecuteReader()).Returns(readerMock.Object).Verifiable();

    var parameterMock = new Mock<IDbDataParameter>();
    commandMock.Setup(m => m.CreateParameter()).Returns(parameterMock.Object);
    commandMock.Setup(m => m.Parameters.Add(It.IsAny<IDbDataParameter>())).Verifiable();

    var connectionMock = new Mock<IDbConnection>();
    connectionMock.Setup(m => m.CreateCommand()).Returns(commandMock.Object);

    var data = new Data(() => connectionMock.Object);
    var result = data.FindAll();
    Console.WriteLine(result);
}

错误

因依赖关系出现问题，已添加 System.Data.SqlClient，随后出现另一个错误。

System.InvalidCastException: Unable to cast object of type 'Castle.Proxies.IDbConnectionProxy' to type 'System.Data.SqlClient.SqlConnection'.

指向这一行

using (var command = new SqlCommand(sql, (SqlConnection) connection))

Answer 1

被测目标方法应重构为依赖抽象而不是实现问题。

例如

public class Data {
    private Func<IDbConnection> Factory { get; }

    public Data(Func<IDbConnection> factory) {
        Factory = factory;
    }

    public IList<Customer> FindAll() {
        using (IDbConnection connection = Factory.Invoke()) {
            const string sql = "SELECT Id, Name FROM Customer";
            using (IDbCommand command = connection.CreateCommand()) {                    
                command.CommandText = sql;

                connection.Open();
                using (IDataReader reader = command.ExecuteReader()) {
                    IList<Customer> rows = new List<Customer>();
                    while (reader.Read()) {
                        rows.Add(new Customer {
                            Id = reader.GetInt32(reader.GetOrdinal("Id")),
                            Name = reader.GetString(reader.GetOrdinal("Name"))
                        });
                    }
                    return rows;
                }
            }
        }
    }
}

从那里可以模拟抽象以在单元测试隔离时按预期行为。

[TestClass]
public class DataTests{
    [TestMethod]
    public void Should_Return_Customer() {
        //Arrange
        var readerMock = new Mock<IDataReader>();

        readerMock.SetupSequence(_ => _.Read())
            .Returns(true)
            .Returns(false);

        readerMock.Setup(reader => reader.GetOrdinal("Id")).Returns(0);
        readerMock.Setup(reader => reader.GetOrdinal("Name")).Returns(1);

        readerMock.Setup(reader => reader.GetInt32(It.IsAny<int>())).Returns(1);
        readerMock.Setup(reader => reader.GetString(It.IsAny<int>())).Returns("Hello World");

        var commandMock = new Mock<IDbCommand>();            
        commandMock.Setup(m => m.ExecuteReader()).Returns(readerMock.Object).Verifiable();

        var connectionMock = new Mock<IDbConnection>();
        connectionMock.Setup(m => m.CreateCommand()).Returns(commandMock.Object);

        var data = new Data(() => connectionMock.Object);

        //Act
        var result = data.FindAll();

        //Assert - FluentAssertions
        result.Should().HaveCount(1);
        commandMock.Verify(); //since it was marked verifiable.
    }
}

对于集成测试，与数据库的实际连接可用于验证功能

var data = new Data(() => new SqlConnection("live connection string here"));

将在生产中使用相同的方法连接到服务器。

使用 MsTest 在 C# 中模拟 SqlConnection、SqlCommand 和 SqlReader

Mocking SqlConnection, SqlCommand and SqlReader in C# using MsTest

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