SaveAs for Assembly and parts into new directory

I'm writing some tests for an addin.  After I make my changes to the document, I want to save the whole assembly.  However, I don't want to change the original set of files, so I want to save the assembly heirarchy into a new directory.  Through the UI, the save as command allows me to select the all the parts and save them to a new directory.  Here's the macro that I wrote to do the same, but it only saves the main sldasm and nothing else.

Option Explicit

Sub main()

    Dim swApp                       As SldWorks.SldWorks
    Dim swModel                     As SldWorks.ModelDoc2
    Dim swPart As SldWorks.PartDoc
    Dim swModelDocExt       As SldWorks.ModelDocExtension
    Dim boolstatus          As Boolean
    Dim filename            As String
    Dim lErrors             As Long
    Dim lWarnings           As Long


    Set swApp = Application.SldWorks
    Set swModel = swApp.ActiveDoc
    Set swModelDocExt = swModel.Extension
   
    filename = "C:\\Temp\\test.sldasm"
'    filename = "C:\\Temp\\"  ' Gives error
'    filename = "C:\\Temp"  ' Gives error
    boolstatus = swModelDocExt.SaveAs(filename, swSaveAsCurrentVersion, swSaveAsOptions_SaveReferenced + swSaveAsOptions_Copy, _
        Nothing, lErrors, lWarnings)

    Debug.Print boolstatus, lErrors, lWarnings
   
End Sub

I also tried removing the _Copy option.  No difference.
SolidworksApi macros