Moles to mock an indexed property

Question

I am looking for a way to 'detour' a single item in a configuration file with Moles. I can do this:

         NameValueCollection appsettings = new NameValueCollection();
         appSettings.Add("MyKey", "MyValue");
         System.Configuration.Moles.MConfigurationManager.AppSettingsGet = () => this.appSettings;

This works fine, however the class which I am trying to test uses some other configuration settings including ConfigSections and the Moles detour seems to have broken this. I only want to replace a specific value, not the whole section. In TypeMock, I could do this:

Isolate.WhenCalled(() => ConfigurationManager.AppSettings["MyKey"]).WithExactArguments().WillReturn("MyValue");

When I mock the configurationManager using TypeMock, my test passes, but when I use the Moles version (which looks like it should do the same thing) it fails meaning that Moles must be affecting the ConfigurationManager class in a way which TypeMock doesn't.

Any help on how I can use moles to just behave in the way which TypeMock does would be greatly appreciated.

Which version of Moles are you using? Is it v0.94.51023.0 by chance? There are issues with that build and the ConfigurationManager. Have you tried using v0.94.51006.1? — Matt, Jun 30 '11 at 16:29
Thanks Matt, I am indeed using 0.94.51023.0. I have tried to get 51006.1 so I can see if the issue exists in that version, but can't find a download anywhere. I have now managed to narrow my problem down to static constructors. Moles is correctly mocking ConfigurationManager in instance members, but when ConfigurationManager is called from a static constructor, Moles is not mocking it correctly. I have posted a separate thread for this issue at: http://stackoverflow.com/questions/6015173/how-use-moles-for-a-constructor — user450354, Jul 01 '11 at 09:09

tecfield · Answer 1 · 2012-04-26T17:46:58.483

make a copy of current app.settings section:

NameValueCollection appSettings = new NameValueCollection(ConfigurationManager.AppSettings);

Modify the part you need by calling Set/Add function (keep in mind that 'Add' function does not overwrite existing values but it adds a new value for the key. On the other hand, 'Set' always creates a new entry and gets rid of the existing values):
```
appSettings.Set("key name", "new value");
```

Create the delegate:

MConfigurationManager.AppSettingsGet =
  () =>
  {
    return appSettings;
  };

Moles to mock an indexed property

1 Answers1