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社区首页 >问答首页 >如果存在默认构造函数,则没有默认构造函数错误。

如果存在默认构造函数,则没有默认构造函数错误。
EN

Stack Overflow用户
提问于 2014-03-14 19:23:10
回答 3查看 703关注 0票数 2

编辑:准备公开生产代码!希望没人偷我的秘密!

我有一个Controller类,用于使用Modbus协议通过TCP与设备通信。我使用NModbus库。

下面是控制器类实现的接口:

代码语言:javascript
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public interface CoilReader
{
    bool[] Read(ushort startAddress, ushort numberOfCoils);
}

public interface CoilWriter
{
    void WriteSingle(ushort address, bool value);

    void WriteMultiple(ushort startAddress, bool[] values);
}

public interface HoldingRegisterReader
{
    ushort[] Read(ushort startAddress, ushort numberOfRegisters);
}

public interface HoldingRegisterWriter
{
    void WriteSingle(ushort address, ushort value);

    void WriteMultiple(ushort startAddress, ushort[] values);
}

public interface InputReader
{
    bool[] Read(ushort startAddress, ushort numberOfCoils);
}

public interface InputRegisterReader
{
    ushort[] Read(ushort startAddress, ushort numberOfRegisters);
}

public interface ConnectionInfo
{
    string IP { get; set; }
}

这是控制器类。

代码语言:javascript
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using System;
using System.Net.Sockets;
using System.Reflection;
using global::Modbus.Device;

public class Controller
    : ConnectionInfo,
      HoldingRegisterReader,
      InputRegisterReader,
      CoilReader,
      InputReader,
      CoilWriter,
      HoldingRegisterWriter
{
    static Controller()
    {
        AppDomain.CurrentDomain.AssemblyResolve += (sender, e) => loadEmbeddedAssembly(e.Name);
    }

    public virtual string IP
    {
        get
        {
            return this.ip;
        }

        set
        {
            this.ip = value;
        }
    }

    public virtual ushort[] ReadHoldingRegisters(ushort startAddress, ushort numberOfRegisters)
    {
        using (var connection = this.createDeviceConnection())
        {
            return connection.ReadHoldingRegisters(startAddress, numberOfRegisters);
        }
    }

    public virtual ushort[] ReadInputRegisters(ushort startAddress, ushort numberOfRegisters)
    {
        using (var connection = this.createDeviceConnection())
        {
            return connection.ReadInputRegisters(startAddress, numberOfRegisters);
        }
    }

    public virtual bool[] ReadCoils(ushort startAddress, ushort numberOfCoils)
    {
        using (var connection = this.createDeviceConnection())
        {
            return connection.ReadCoils(startAddress, numberOfCoils);
        }
    }

    public virtual bool[] ReadInputs(ushort startAddress, ushort numberOfInputs)
    {
        using (var connection = this.createDeviceConnection())
        {
            return connection.ReadInputs(startAddress, numberOfInputs);
        }
    }

    public virtual void WriteSingleCoil(ushort address, bool value)
    {
        using (var connection = this.createDeviceConnection())
        {
            connection.WriteSingleCoil(address, value);
        }
    }

    public virtual void WriteMultipleCoils(ushort startAddress, bool[] values)
    {
        using (var connection = this.createDeviceConnection())
        {
            connection.WriteMultipleCoils(startAddress, values);
        }
    }

    public virtual void WriteSingleHoldingRegister(ushort address, ushort value)
    {
        using (var connection = this.createDeviceConnection())
        {
            connection.WriteSingleRegister(address, value);
        }
    }

    public virtual void WriteMultipleHoldingRegisters(ushort startAddress, ushort[] values)
    {
        using (var connection = this.createDeviceConnection())
        {
            connection.WriteMultipleRegisters(startAddress, values);
        }
    }

    string ConnectionInfo.IP
    {
        get
        {
            return this.IP;
        }

        set
        {
            this.IP = value;
        }
    }

    ushort[] HoldingRegisterReader.Read(ushort startAddress, ushort numberOfRegisters)
    {
        return this.ReadHoldingRegisters(startAddress, numberOfRegisters);
    }

    ushort[] InputRegisterReader.Read(ushort startAddress, ushort numberOfRegisters)
    {
        return this.ReadInputRegisters(startAddress, numberOfRegisters);
    }

    bool[] CoilReader.Read(ushort startAddress, ushort numberOfCoils)
    {
        return this.ReadCoils(startAddress, numberOfCoils);
    }

    bool[] InputReader.Read(ushort startAddress, ushort numberOfInputs)
    {
        return this.ReadInputs(startAddress, numberOfInputs);
    }

    void CoilWriter.WriteSingle(ushort address, bool value)
    {
        this.WriteSingleCoil(address, value);
    }

    void CoilWriter.WriteMultiple(ushort startAddress, bool[] values)
    {
        this.WriteMultipleCoils(startAddress, values);
    }

    void HoldingRegisterWriter.WriteSingle(ushort address, ushort value)
    {
        this.WriteSingleHoldingRegister(address, value);
    }

    void HoldingRegisterWriter.WriteMultiple(ushort startAddress, ushort[] values)
    {
        this.WriteMultipleHoldingRegisters(startAddress, values);
    }

    private ModbusIpMaster createDeviceConnection()
    {
        const int port = 502;
        var client = new TcpClient();
        client.BeginConnect(this.ip, port, null, null).AsyncWaitHandle.WaitOne(TimeSpan.FromSeconds(2));
        if (!client.Connected)
        {
            throw new Exception("Cannot connect to " + this.ip + ":" + port);
        }

        return ModbusIpMaster.CreateIp(client);
    }

    private static Assembly loadEmbeddedAssembly(string name)
    {
        if (name.EndsWith("Retargetable=Yes"))
        {
            return Assembly.Load(new AssemblyName(name));
        }

        var container = Assembly.GetExecutingAssembly();
        var path = new AssemblyName(name).Name + ".dll";

        using (var stream = container.GetManifestResourceStream(path))
        {
            if (stream == null)
            {
                return null;
            }

            var bytes = new byte[stream.Length];
            stream.Read(bytes, 0, bytes.Length);
            return Assembly.Load(bytes);
        }
    }

    private string ip;
}

在包含该类及其接口的库中,测试项目中创建的测试与包含该类及其接口的库中创建的测试没有出现以下错误。但是,在一个使用库的不同解决方案中的项目中,我得到了以下内容:

代码语言:javascript
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------ Test started: Assembly: CareControls.IvisHmi.Tests.dll ------

Unknown .NET Framework Version: v4.5.1
Test 'CareControls.IvisHmi.Tests.Presenters.ModbusTcpTogglePresenterTests.FactMethodName' failed:     FakeItEasy.Core.FakeCreationException : 
Failed to create fake of type "CareControls.Modbus.Tcp.Controller".

Below is a list of reasons for failure per attempted constructor:
  No constructor arguments failed:
    No default constructor was found on the type CareControls.Modbus.Tcp.Controller.

If either the type or constructor is internal, try adding the following attribute to the assembly:
[assembly: InternalsVisibleTo("DynamicProxyGenAssembly2")]


at FakeItEasy.Core.DefaultExceptionThrower.ThrowFailedToGenerateProxyWithResolvedConstructors(Type typeOfFake, String reasonForFailureOfUnspecifiedConstructor, IEnumerable`1 resolvedConstructors)
at FakeItEasy.Creation.FakeObjectCreator.TryCreateFakeWithDummyArgumentsForConstructor(Type typeOfFake, FakeOptions fakeOptions, IDummyValueCreationSession session, String failReasonForDefaultConstructor, Boolean throwOnFailure)
at FakeItEasy.Creation.FakeObjectCreator.CreateFake(Type typeOfFake, FakeOptions fakeOptions, IDummyValueCreationSession session, Boolean throwOnFailure)
at FakeItEasy.Creation.DefaultFakeAndDummyManager.CreateFake(Type typeOfFake, FakeOptions options)
at FakeItEasy.Creation.DefaultFakeCreatorFacade.CreateFake[T](Action`1 options)
at FakeItEasy.A.Fake[T]()
Presenters\ModbusTcpTogglePresenterTests.cs(22,0): at CareControls.IvisHmi.Tests.Presenters.ModbusTcpTogglePresenterTests.FactMethodName()

0 passed, 1 failed, 0 skipped, took 0.93 seconds (xUnit.net 1.9.2 build 1705).

这是一个考验:

代码语言:javascript
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namespace CareControls.IvisHmi.Tests.Presenters
{
    using CareControls.IvisHmi.Framework;
    using CareControls.IvisHmi.Presenters;
    using CareControls.IvisHmi.UI;
    using CareControls.Modbus.Tcp;
    using FakeItEasy;
    using Ploeh.AutoFixture;
    using Xunit;

    public class ModbusTcpTogglePresenterTests
    {
        [Fact]
        public void FactMethodName()
        {
            A.Fake<Controller>();
        }
    }
}

为什么FakeItEasy不认为类中存在默认构造函数?

很抱歉有这么大的帖子,但我被要求包括密码。

编辑:如果我在new Controller()行前面添加A.Fake<Controller>(),测试就通过了:

代码语言:javascript
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复制
namespace CareControls.IvisHmi.Tests.Presenters
{
    using CareControls.IvisHmi.Framework;
    using CareControls.IvisHmi.Presenters;
    using CareControls.IvisHmi.UI;
    using CareControls.Modbus.Tcp;
    using FakeItEasy;
    using Ploeh.AutoFixture;
    using Xunit;

    public class ModbusTcpTogglePresenterTests
    {
        [Fact]
        public void FactMethodName()
        {
            new Controller();
            A.Fake<Controller>();
        }
    }
}
EN

回答 3

Stack Overflow用户

回答已采纳

发布于 2014-03-20 16:15:45

我通过将createDeviceConnection()方法转换为NModbusDeviceConnection一次性类来解决这个问题。在NModbusDeviceConnection的静态构造函数中,AssemblyResolve事件是订阅的地方。现在,我可以在不触发Controller程序集加载的情况下创建伪Modbus

有关详细信息,以下是NModbusDeviceConnection类:

代码语言:javascript
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// ---------------------------------------------------------------------------------------------------------------------
// <copyright file="NModbusDeviceConnection.cs" company="Care Controls">
//   Copyright (c) Care Controls Inc. All rights reserved.
// </copyright>
// ---------------------------------------------------------------------------------------------------------------------

namespace CareControls.Modbus.Tcp.Internal
{
    using System;
    using System.Net.Sockets;
    using System.Reflection;
    using global::Modbus.Device;

    internal sealed class NModbusDeviceConnection : IDisposable
    {
        static NModbusDeviceConnection()
        {
            AppDomain.CurrentDomain.AssemblyResolve += (sender, e) => loadEmbeddedAssembly(e.Name);
        }

        public NModbusDeviceConnection(string ip)
        {
            const int port = 502;
            var client = new TcpClient();
            client.BeginConnect(ip, port, null, null).AsyncWaitHandle.WaitOne(TimeSpan.FromSeconds(2));
            if (!client.Connected)
            {
                throw new Exception("Cannot connect to " + ip + ":" + port);
            }

            this.connection = ModbusIpMaster.CreateIp(client);
        }

        public ushort[] ReadHoldingRegisters(ushort startAddress, ushort numberOfRegisters)
        {
            return this.connection.ReadHoldingRegisters(startAddress, numberOfRegisters);
        }

        public ushort[] ReadInputRegisters(ushort startAddress, ushort numberOfRegisters)
        {
            return this.connection.ReadInputRegisters(startAddress, numberOfRegisters);
        }

        public bool[] ReadCoils(ushort startAddress, ushort numberOfCoils)
        {
            return this.connection.ReadCoils(startAddress, numberOfCoils);
        }

        public bool[] ReadInputs(ushort startAddress, ushort numberOfInputs)
        {
            return this.connection.ReadInputs(startAddress, numberOfInputs);
        }

        public void WriteSingleCoil(ushort address, bool value)
        {
            this.connection.WriteSingleCoil(address, value);
        }

        public void WriteMultipleCoils(ushort startAddress, bool[] values)
        {
            this.connection.WriteMultipleCoils(startAddress, values);
        }

        public void WriteSingleHoldingRegister(ushort address, ushort value)
        {
            this.connection.WriteSingleRegister(address, value);
        }

        public void WriteMultipleHoldingRegisters(ushort address, ushort[] values)
        {
            this.connection.WriteMultipleRegisters(address, values);
        }

        public void Dispose()
        {
            if (this.connection != null)
            {
                this.connection.Dispose();
            }
        }

        private static Assembly loadEmbeddedAssembly(string name)
        {
            if (name.EndsWith("Retargetable=Yes"))
            {
                return Assembly.Load(new AssemblyName(name));
            }

            var container = Assembly.GetExecutingAssembly();
            var path = new AssemblyName(name).Name + ".dll";

            using (var stream = container.GetManifestResourceStream(path))
            {
                if (stream == null)
                {
                    return null;
                }

                var bytes = new byte[stream.Length];
                stream.Read(bytes, 0, bytes.Length);
                return Assembly.Load(bytes);
            }
        }

        private readonly ModbusIpMaster connection;
    }
}

下面是修改后的Controller类:

代码语言:javascript
运行
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// ---------------------------------------------------------------------------------------------------------------------
// <copyright file="Controller.cs" company="Care Controls">
//   Copyright (c) Care Controls Inc. All rights reserved.
// </copyright>
// ---------------------------------------------------------------------------------------------------------------------

namespace CareControls.Modbus.Tcp
{
    using System;
    using CareControls.Modbus.Tcp.Internal;

    public class Controller
        : ConnectionInfo,
          HoldingRegisterReader,
          InputRegisterReader,
          CoilReader,
          InputReader,
          CoilWriter,
          HoldingRegisterWriter
    {
        public Controller()
        {
            this.newDeviceConnection = () => new NModbusDeviceConnection(this.IP);
        }

        public virtual string IP { get; set; }

        public virtual ushort[] ReadHoldingRegisters(ushort startAddress, ushort numberOfRegisters)
        {
            using (var connection = this.newDeviceConnection())
            {
                return connection.ReadHoldingRegisters(startAddress, numberOfRegisters);
            }
        }

        public virtual ushort[] ReadInputRegisters(ushort startAddress, ushort numberOfRegisters)
        {
            using (var connection = this.newDeviceConnection())
            {
                return connection.ReadInputRegisters(startAddress, numberOfRegisters);
            }
        }

        public virtual bool[] ReadCoils(ushort startAddress, ushort numberOfCoils)
        {
            using (var connection = this.newDeviceConnection())
            {
                return connection.ReadCoils(startAddress, numberOfCoils);
            }
        }

        public virtual bool[] ReadInputs(ushort startAddress, ushort numberOfInputs)
        {
            using (var connection = this.newDeviceConnection())
            {
                return connection.ReadInputs(startAddress, numberOfInputs);
            }
        }

        public virtual void WriteSingleCoil(ushort address, bool value)
        {
            using (var connection = this.newDeviceConnection())
            {
                connection.WriteSingleCoil(address, value);
            }
        }

        public virtual void WriteMultipleCoils(ushort startAddress, bool[] values)
        {
            using (var connection = this.newDeviceConnection())
            {
                connection.WriteMultipleCoils(startAddress, values);
            }
        }

        public virtual void WriteSingleHoldingRegister(ushort address, ushort value)
        {
            using (var connection = this.newDeviceConnection())
            {
                connection.WriteSingleHoldingRegister(address, value);
            }
        }

        public virtual void WriteMultipleHoldingRegisters(ushort startAddress, ushort[] values)
        {
            using (var connection = this.newDeviceConnection())
            {
                connection.WriteMultipleHoldingRegisters(startAddress, values);
            }
        }

        string ConnectionInfo.IP
        {
            get
            {
                return this.IP;
            }

            set
            {
                this.IP = value;
            }
        }

        ushort[] HoldingRegisterReader.Read(ushort startAddress, ushort numberOfRegisters)
        {
            return this.ReadHoldingRegisters(startAddress, numberOfRegisters);
        }

        ushort[] InputRegisterReader.Read(ushort startAddress, ushort numberOfRegisters)
        {
            return this.ReadInputRegisters(startAddress, numberOfRegisters);
        }

        bool[] CoilReader.Read(ushort startAddress, ushort numberOfCoils)
        {
            return this.ReadCoils(startAddress, numberOfCoils);
        }

        bool[] InputReader.Read(ushort startAddress, ushort numberOfInputs)
        {
            return this.ReadInputs(startAddress, numberOfInputs);
        }

        void CoilWriter.WriteSingle(ushort address, bool value)
        {
            this.WriteSingleCoil(address, value);
        }

        void CoilWriter.WriteMultiple(ushort startAddress, bool[] values)
        {
            this.WriteMultipleCoils(startAddress, values);
        }

        void HoldingRegisterWriter.WriteSingle(ushort address, ushort value)
        {
            this.WriteSingleHoldingRegister(address, value);
        }

        void HoldingRegisterWriter.WriteMultiple(ushort startAddress, ushort[] values)
        {
            this.WriteMultipleHoldingRegisters(startAddress, values);
        }

        private readonly Func<NModbusDeviceConnection> newDeviceConnection;
    }
}
票数 0
EN

Stack Overflow用户

发布于 2014-03-14 19:59:23

根据这一点:

伪造/模拟接口会产生“没有默认构造函数”的错误,这怎么可能呢?

有一个错误,可能会给出错误的异常消息。他们说,在这种情况下,仍然应该有导致异常被抛出的东西。

我的建议是:

  • 添加显式默认构造函数有帮助吗?
  • 您能正常地成功实例化类吗?
  • 您能用反射或Activator.CreateInstance成功地实例化类吗?
票数 2
EN

Stack Overflow用户

发布于 2014-03-14 20:46:56

静态构造函数与公共构造函数不是一回事。您确定在定义静态构造函数时编译器生成默认的公共构造函数吗?我没想到你会两者兼得。如果你逆向工程装配,它会出现吗?

静态构造函数很可能被称为“懒惰”,因此当FakeItEasy试图通过对类型进行反射来创建假构造函数时,静态构造函数还没有被调用。这将解释为什么在创建假之前实例化类型时它会工作。

票数 1
EN
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接:

https://stackoverflow.com/questions/22413998

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