More Fun with Shims

I'm finally back to doing some server side code (as opposed to the client stuff I've been working exclusively with for several months) and I found myself in need of some unit tests.  It's been a long time since I used a shim from Microsoft's Fakes framework so I had to poke and prod it for a while to work and I don't want to forget what I did.  Here goes:

In this particular example I was working with the WSUS API provided by Microsoft to interact with WSUS.  I specifically was trying to save a new signing certificate, but I obviously didn't want to actually do that on a WSUS server.  The solution was to use shims and stubs this time.

   1:  private string _fileNameParameter = "empty";

   2:  private SecureString _passwordParameter = new SecureString();

   1:  private StubIUpdateServer PrepareIUpdateServerStub()

   2:  {

   3:      FakesDelegates.Action<string, SecureString> setSigningCertificateAction = (fileName, password) =>

   4:      {

   5:          _fileNameParameter = fileName;

   6:          _passwordParameter = password;

   7:      };

   8:   

   9:      var iUpdateServerConfiguration = new StubIUpdateServerConfiguration

  10:      {

  11:          SetSigningCertificateStringSecureString = setSigningCertificateAction

  12:      };

  13:   

  14:      var iUpdateServerStub = new StubIUpdateServer

  15:      {

  16:          GetConfiguration = () => iUpdateServerConfiguration

  17:      };

  18:   

  19:      return iUpdateServerStub;

  20:  }

   1:  [TestMethod]

   2:  public void SetSigningCertificateShouldPassParametersToWsusApiAndReturnTrue()

   3:  {

   4:      using (ShimsContext.Create())

   5:      {

   6:          // arrange

   7:          const string expectedFileName = "fileName";

   8:          const string expectedPasswordString = "password";

   9:          var expectedPassword = new SecureString();

  10:          foreach (var c in expectedPasswordString)

  11:          {

  12:              expectedPassword.AppendChar(c);

  13:          }

  14:   

  15:          ShimAdminProxy.GetUpdateServerStringBooleanInt32 = (name, isSsl, port) => PrepareIUpdateServerStub();

  16:   

  17:          var wsusRepository = new WsusRepository();

  18:   

  19:          // act

  20:          var result = wsusRepository.SetSigningCertificate(expectedFileName, expectedPassword);

  21:   

  22:          // assert

  23:          Assert.AreEqual(expectedFileName, _fileNameParameter);

  24:          Assert.AreEqual(expectedPassword.ToString(), _passwordParameter.ToString());

  25:          Assert.IsTrue(result);

  26:      }

  27:  }

I broke out a bunch of the stub creation stuff so I could reuse it across multiple tests.  That's what the PrepareIUpdateServerStub method is for.  That's also why I have the global variables _fileNameParameter and _passwordParameter.  The method I was testing is essentially a pass-through to the WSUS API that we reuse in multiple applications so the method itself was fairly straightforward (check if a file and password were passed, then pass them on to WSUS).

Like I said at the beginning, working with Shims, Fakes, and Stubs is always a challenge for me so hopefully this documentation will help me next time I need to do it.