Acdbmgd.dll exceptions when Unit Testing
If your code snippet uses AutoCAD APIs, then you cannot really do a "UNIT" test. The test can only run with AutoCAD itself being integrated (thus, the test is INTEGRATED TEST), because all the classed in Acdbmgd.dll only available in a running AutoCAD process.
So, doing real "unit test" with AutoCAD add-in code is very difficult and tricky. One needs to structure the code properly to separate the portions of code that are "unit-test-able" (i.e. some business logic that does not involve AutoCAD). As you can see, for most part of AutoCAD add-in code, separating the code into "unit-test-able" (without AutoCAD involved) is really hard, sometimes not possible/not realistically doable, IMO.
In your case, if you still want to test with your existing AutoCAD .NET code, your test project must run AutoCAD, which effectively turn your "unit" test into "integration test", but, it may still better than "no test", right? Or you take pains to re-organize the code in your AutoCAD add-in DLL project, and to only flag code that has nothing to do with AutoCAD .NET API as testable and only test that portion of code (I guess there would not be much code left as "test-able").
Also, there may be third party test tool available to help integrate apps, such as AutoCAD, into the test process, so that you can test your code like "Unit Test" (while behind the scene, it is integration test, anyway). I have never bothered to try.
Accepted solution
I am not sure whether you get my point or not: AutoCAD .NET API assemblies (acdmmgd.dll...) can ONLY be USED WHEN LOADING INTO AutoCAD process.
In your case, your test project that loads your DLL project (to test), which has acdbmgd.dll referenced. Whether the code actually has Point3d actually used or not, the acdbmgd.dll has to be loaded into memory of "NON-AutoCAD" process, thus the error, meaning you CANNOT use Acdbmgd.dll in ANY WAY outside AutoCAD process.
