Chapter 6 / 1
Chapter 6 / 2
Chapter 6 / 3
Chapter 6 / 3 - add ASSERT_THROW() macro.
Chapter 6 / 4 - add boost::gregorian::date stub

initially the original header from boost.
Chapter 6 / 4 - minimal implementation

of boost::gregorian::date stub to facilitate compilation.
Chapter 6 / 4 - make test pass.
Chapter 6 / 5
Chapter 6 / 5 - make test pass.
Chapter 6 / 6
Chapter 6 / 7
Chapter 6 / 8