如何模拟 SerialDataReceivedEventArgs

Question

我有一个外设驱动程序，它使用串行端口与外围设备进行通信。我想对该驱动程序进行单元测试并尝试模拟串行端口。因此，我为框架类型 SerialPort 创建了一个包装器，以使其实现一个接口：

public interface IScannerPort
{
    Handshake Handshake { get; set; }
    bool IsOpen { get; }

    event SerialDataReceivedEventHandler DataReceived;

    void Close( );
    void Open( );
    string ReadLine( );
}

现在我使用起订量创建了一个模拟：

Mock<IScannerPort> scannerPort = new Mock<IScannerPort>( );

然后我想引发 DataReceived 事件。但 SerialDataReceivedEventArgs 不允许我设置 EventType 属性。所以我也尝试模拟 SerialDataReceivedEventArgs，最终得到

Mock<SerialDataReceivedEventArgs> args = new Mock<SerialDataReceivedEventArgs>();
args.SetupProperty(a => a.EventType, SerialData.Eof);

But the second line raises a NotSupportedException: Invalid setup on a non-virtual (overridable in VB) member: a =>; a.EventType

如何引发事件？或者我如何模拟事件参数？

Answer 1

SerialDataReceivedEventArgs 不一定会被模拟。可以使用反射创建它的实例：

ConstructorInfo constructor = typeof (SerialDataReceivedEventArgs).GetConstructor(
    BindingFlags.NonPublic | BindingFlags.Instance,
    null,
    new[] {typeof (SerialData)},
    null);

SerialDataReceivedEventArgs eventArgs = 
    (SerialDataReceivedEventArgs)constructor.Invoke(new object[] {SerialData.Eof});

然后可以使用通风参数的“真实”实例在模拟实例上引发事件：

scannerPort.Raise( s => s.DataReceived += null, eventArgs );

Answer 2

我想我可能已经通过回答如何引发事件部分解决了您的问题，如下所示：

  var mockedScannerPort = new Mock<IScannerPort>();

            mockedScannerPort.Setup(sp => sp.ReadLine())
                             .Returns("123")
                             .Raises(sp => sp.DataReceived += null, new object[] { this, It.IsAny<SerialDataReceivedEventArgs>() });

            bool mockEventWasInvoked = false;
            mockedScannerPort.Object.DataReceived += (sedner, e) => mockEventWasInvoked = true;
            var retVal = mockedScannerPort.Object.ReadLine();

            Assert.AreEqual( "123", retVal );
            Assert.IsTrue(mockEventWasInvoked);

模拟 SerialDataReceivedEventArgs 有点棘手，因为它没有默认构造函数。我很快就会尝试一个解决方法。

编辑：感谢@PVitt 提供存根 SerialDataEventArgs 的解决方法。将其发布在这里只是为了完整性。

[Test]
        public void Test()
        {
            var mockedScannerPort = new Mock<IScannerPort>();

            var constructor = typeof(SerialDataReceivedEventArgs).GetConstructor(BindingFlags.NonPublic | BindingFlags.Instance, null, new[] { typeof(SerialData) }, null);
            var eventArgs = (SerialDataReceivedEventArgs)constructor.Invoke(new object[] { SerialData.Eof });

            mockedScannerPort.Setup(sp => sp.ReadLine())
                             .Returns("123")
                             .Raises(sp => sp.DataReceived += null, new object[] { this, eventArgs });

            bool mockEventWasInvoked = false;
            SerialDataReceivedEventArgs ea = null;
            mockedScannerPort.Object.DataReceived += (sedner, e) =>
                                                         {
                                                             mockEventWasInvoked = true;
                                                             ea = e;
                                                         };

            var retVal = mockedScannerPort.Object.ReadLine();

            Assert.AreEqual( "123", retVal );
            Assert.IsTrue(mockEventWasInvoked);
            Assert.IsNotNull( ea );
            Assert.AreEqual( ea.EventType, SerialData.Eof );
        }