单元测试w/Moq of Excel Interop + Type.Missing

Question

我刚刚遇到一个例外，写单元测试时我无法解释自己。

（简化）代码，我想测试的是：

public object GetSecondColumn(Microsoft.Office.Interop.Excel.Range theRange) 
{ 
    return theRange.Columns[2, Type.Missing]; 
} 

我试着写这个测试，但我不断收到一个例外：

//Arrange 
var usedRange = new Mock<Range>(); 
var result = new Mock<Range>(); 
usedRange .Setup(m => m[It.IsAny<object>(), It.IsAny<object>()]).Returns(
    (object r, object c) => 
    { 
     return result.Object; 
    }); 

//Assert 
GetSecondColumn(usedRange); 

方法的调用抛出：

System.ArgumentException 
Message=Missing parameter does not have a default value. 
Parameter name: parameters 
    StackTrace: 
     at System.Reflection.MethodBase.CheckArguments(Object[] parameters, Binder binder, BindingFlags invokeAttr, CultureInfo culture, Signature sig) 
     at System.Reflection.RuntimeMethodInfo.InvokeArgumentsCheck(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture) 
     at System.Delegate.DynamicInvokeImpl(Object[] args) 
     at System.Delegate.DynamicInvoke(Object[] args) 
     at Moq.Extensions.InvokePreserveStack(Delegate del, Object[] args) 
     at Moq.MethodCallReturn`2.Execute(ICallContext call) 
     at Moq.ExecuteCall.HandleIntercept(ICallContext invocation, InterceptorContext ctx, CurrentInterceptContext localctx) 
     at Moq.Interceptor.Intercept(ICallContext invocation) 
     at Moq.Proxy.CastleProxyFactory.Interceptor.Intercept(IInvocation invocation) 
     at Castle.DynamicProxy.AbstractInvocation.Proceed() 
     at Castle.Proxies.ObjectProxy_3.get__Default(Object RowIndex, Object ColumnIndex) 
     at **** 

无法使用It.IsAny（）处理Type.Missing/Missing.Value吗？

Answer 1

IMO您缺少Columns方法的Setup。此方法需要设置，因为它在函数GetSecondColumn中调用。如果没有设置Columns是null：

所以设置了Columns例如喜欢这个。这里的Columns返回expected为object类型的任何参数。 HTH

[TestMethod] 
public void GetSecondColumn_WhenCalled_ReturnsSomeExpectedResult() 
{ 
    // Arrange 
    const string expected = "Expectd Value To Return"; 
    var rangeMock = new Mock<Range>(); 
    var fakeResultRange = new Mock<Range>(); 
    fakeResultRange.Setup(range => range[It.IsAny<object>(), It.IsAny<object>()]).Returns(expected); 
    rangeMock.Setup(range => range.Columns).Returns(() => fakeResultRange.Object); 
    ClassToUnitTest cut = new ClassToUnitTest(); 

    // Act 
    var actual = cut.GetSecondColumn(rangeMock.Object); 

    // Assert 
    Assert.AreEqual(expected, actual); 
}