public IEnumerable<TestCaseData> Should_Return1stDay_WhenCalledStartOfMonth_TestCaseSource()
{
//all months
yield return new TestCaseData(new DateTime(2012, 1, 10));
yield return new TestCaseData(new DateTime(2012, 2, 1));
yield return new TestCaseData(new DateTime(2012, 3, 19));
yield return new TestCaseData(new DateTime(2012, 4, 20));
yield return new TestCaseData(new DateTime(2012, 5, 30));
yield return new TestCaseData(new DateTime(2012, 6, 11));
yield return new TestCaseData(new DateTime(2012, 7, 15));
yield return new TestCaseData(new DateTime(2012, 8, 8));
yield return new TestCaseData(new DateTime(2012, 9, 4));
yield return new TestCaseData(new DateTime(2012, 10, 6));
yield return new TestCaseData(new DateTime(2012, 12, 19));
yield return new TestCaseData(new DateTime(2012, 12, 24));
}