c#：自动测试中的 DllImport 问题

Question

i have a method registered like this:

    [DllImport("MyApi.dll", CharSet = CharSet.Ansi)]
    private static extern int SomeRandomCall();

and i added the MyApi.dll to the project with "Copy always = true" and locally everything compiles fine and the MSTest Unittests are working...

But: When i try to run the unittests manually via console, like:

mstest.exe /testcontainer:C:\mytestdll.dll

the tests are failing and that's because mstest ( which finally executes the tests in my dll ) expects the MyApi.dll to be in its directory ( C:\Windows[...]\IDE 7\MSTest.exe )... Ok, makes sense, but:

As C# attributes require constant values as parameters, i can not use sth. like "GetCurDir() + "MyApi.dll"... What is the best solution to handle this "dynamic path to MyApi.dll" problem?

The only thing i can think of right now is conditional compiler symbols, but that's pretty dirty...

Answer 1

The DllImport is fine as it is; what you need to do is make sure the library loader can find MyApi.dll at runtime. One way to accomplish this is with the PATH environment variable:

set PATH=%PATH%;C:\

mstest.exe /testcontainer:C:\mytestdll.dll

...assuming MyApi.dll is in C:\ (not recommended).

Answer 2

Judging from http://bytes.com/topic/c-sharp/answers/440208-dllimport-attribute-where-default-dll-location , you may want to try preloading the library before calling the [DllImport] decorated method with LoadLibrary. Hopefully DLL is found if its already loaded, no matter where its loaded from. You'll need to call LoadLibrary via pinvoke.