Newed a blank Unit Test Project.
Converted MS UnitTesting to NUnit.
Renamed the name of the test class.
Renamed the name of the first test to be WHEN_One_SHOULD_SayOne() and wrote the assertion of the test.
Wrote the given part of the test WHEN_One_SHOULD_SayOne().
Added class WordHandler.
Moved the class WordHandler to another file.
Added method WordHandler.handle().
Renamed method WordHandler.handle() to be WordHandler.Handle().
Added test WHEN_Three_SHOULD_SayFizz().
Made all tests green.
Extracted the duplicated code into the SetUp attribute in the test class FizzBuzzTest.
Added test WHEN_Five_SHOULD_SayBuzz().
Made all tests green.
Added test WHEN_Fifteen_SHOULD_SayFizzBuzz().
Made all tests green.
Renamed class WordHandler to be FizzBuzzHandler.
Extracted super class WordHandler.
Programmed against the interface of the class WordHandler in the test class.
Extracted 2nd method Handle() in class FizzBuzzHandler for holding the remaining logic other than saying FizzBuzz.