It's a TSA Test. There is no possible way you can determine that one test has the correct result and the other doesn't. The test that reads the value should write the value, then read it back. Do not rely on the data to be in any state before the test unless you write the value right there.

>That's the idea - the unit test will setup the data the way I need. Say, I have a method in my class that based on the preference table values makes slightly different things. In order for me to test both preference settings, I need to create two tests and in these tests change these settings. I think I may also need to restore them back after I'm done, but that's not my concern at the moment.