如何对私有静态/共享方法进行单元测试？

Question

As per this answer to Unit testing private methods in C# I am using a PrivateObject to unit test private methods. This generally works really well and is quite easy to use, however it doesn't appear to work if the method is Shared or Static .

I don't really want to make the method public (otherwise I wouldn't even be bothering with PrivateObjects but I'm failing to see another way.

Example vb methods in class being tested:

    Private Sub SampleInstanceMethod(arg as Object)
        'Do something
    End Sub
    Private Shared Sub SampleSharedMethod(arg as Object)
        'Do something
    End Sub

Unit test code

    Dim fooBarPO = New PrivateObject(GetType(FooBar))
    fooBarPO.Invoke("SampleInstanceMethod", {arg1}) ' Works
    fooBarPO.Invoke("SampleSharedMethod", {arg1}) ' Doesn't work

Interested in answers in either C# or VB

Answer 1

You could use PrivateType and InvokeStatic for this:

    Dim foo = New PrivateType(GetType(TestClass))
    foo.InvokeStatic("SampleSharedMethod", {arg1})

If you want to pass parameters ByRef - for instance if the method under test looked something like this:

    Private Shared Sub SampleSharedMethod(ByRef arg As String)
       arg += "abc"
    End Sub

You can use this overload of InvokeStatic to get the results back:

    Dim foo = New PrivateType(GetType(TestClass))
    Dim params() As Object = {"123"}
    foo.InvokeStatic("SampleSharedMethod", params)

    Dim updatedValue = params(0) ' This would be 123abc in this example